But voters will go to the polls Tuesday dozens of states, deciding everything from local tax measures to high-profile races that could impact national politics. In short, Tuesday is the most significant election in the United states since last November, experts say, when President Trump defeated Kamala Harris in the presidential race, and Republicans maintained control of the House and Senate. It’s also being viewed as a way to gauge the pulse of voters a year before the 2026 elections, when control of the House, Senate and governor’s offices will be up for grabs.

“Tuesday has become an early referendum on Trump,” said Larry Gerston, a professor emeritus of political science at San Jose State University. “There are different states, different turnouts and different issues. But that’s the overall theme.”

A CNN poll Monday showed voters aren’t happy. Trump’s approval rating was 37% — the lowest of his second term. A majority of voters said his polices have worsened the economy, hurt America’s standing in the world, and that his immigration crackdown has “gone too far.” But the same voters had an even lower view of the Democratic Party, giving it just a 29% approval rating.

Five key races to watch Tuesday:

1) Proposition 50

Gov. Gavin Newsom’s statewide ballot measure, if approved by voters, would redraw California’s congressional districts in a way that could cost five Republicans their seats, tilting the state’s delegation from the current 43 Democrats and 9 Republicans to 48-4 after next year’s elections. Newsom and Sacramento Democrats placed the measure on the ballot after Trump pushed governors in red states, including Texas, to redraw their district lines this year, instead of every 10 years after the Census, as had been the custom, in an attempt to boost Republicans’ chances of keeping control of the House of Representatives next year.

If Democrats win the House in 2026, they could impeach Trump again, haul his cabinet secretaries under oath before investigations, and block funding for everything from new offshore oil drilling to expanded immigration detention centers. Republicans led by former Gov. Arnold Schwarzenegger — who worked hard to create California’s non-partisan commission that draws district lines — have fought Prop 50. But Democrats have outraised opponents $122 million to $44 million. Polls show the measure leading in California, a state Trump lost by 20 points last November. If it passes, Newsom’s national profile as a 2028 presidential candidate will be boosted.

2) Virginia

Republican Gov. Glenn Youngkin will leave office due to term limits in this purple state. Former congresswoman Abigail Spanberger, a moderate Democrat and former CIA agent who has focused on cost-of-living issues, is running to succeed him against Republican Lt. Gov. Winsome Earle-Sears, a Trump supporter and former Marine. Spanberger is leading in the polls, particularly as the federal government shutdown has hit Virginia residents hard. Whoever wins will be the first female governor in Virginia history.

A big question mark: Whether Democrat Jay Jones can hang on to beat Republican incumbent Jason Miyares in the attorney general’s race. Jones led until last month. But the National Review published text messages Jones sent to a fellow state lawmaker wishing a Republican state leader and his family would die. Jones also was cited in 2022 for driving 116 mph. As part of a plea deal, he performed 500 hours of community service for his own political action committee. His image and poll numbers have suffered.

3) New Jersey

The other marquee governor’s race Tuesday is in the Garden State, where a close battle is playing out. Democrat Mikie Sherrill, a four-term member of Congress and former Navy helicopter pilot, faces Republican Jack Ciattarelli, a former state Assemblyman who came within 3 points of defeating incumbent Democratic Gov. Phil Murphy in 2021.

A normally reliable blue state that has voted for the Democratic nominee for president in every election since 1992, New Jersey has occasionally elected Republicans as governor, most recently Chris Christie in 2009 and 2013. Sherrill holds a narrow lead in the polls. But Harris only defeated Trump there in November by 5.9%, and Ciattarelli, with Trump’s backing and solid fundraising, is looking for a breakthrough win.

4) New York City

Three candidates are vying to run America’s most populous city: Former Gov. Andrew Cuomo, 67, a Democrat who won four statewide elections, only to resign his Albany office in 2021 amid sexual harassment allegations; Republican Curtis Sliwa, 71, who founded the Guardian Angels crimefighting group; and state lawmaker Zohran Mamdani, a 34-year-old Democratic Socialist who has built momentum with charismatic speeches, clever social media and promises to raise taxes on billionaires, provide free bus service and a pass a $30 minimum wage. Mamdani, a darling of progressives nationwide, is leading in the polls, even though many traditional Democratic leaders, including Barack Obama, Hillary Clinton and Senate Minority Leader Chuck Schumer, have not endorsed him or Cuomo.

5) Pennsylvania

Few states are more important in winning the presidency than Pennsylvania. After voting for Obama twice, Keystone State voters shifted to Trump in 2016, embraced Joe Biden in 2020, and veered back to Trump last year, awarding him their 19 electoral votes.

Democrats hold a 5-2 majority on the state Supreme Court. Three Democratic justices — David Wecht, Christine Donohue and Kevin Dougherty — face yes-no retention votes, in which voters will decide whether to keep them on the bench. Republicans are pushing hard to remove them, which would shift the court to a 2-2 tie before elections in 2027 add new members. A deadlocked chamber could have major impacts on the 2028 presidential race if disputes over voting, ballot counting or other elections questions make it to Pennsylvania’s highest court.

The murder of Minnesota Democratic state lawmaker Melissa Hortman and her husband, Mark, in June. An arson fire at Pennsylvania Gov. Josh Shapiro’s house in April. The shooting death of UnitedHealthcare CEO Brian Thompson on a New York sidewalk in December. Before that, the hammer attack that nearly killed Nancy Pelosi’s husband, Paul, at their San Francisco home, and two attempted assassinations of President Trump. The events have shaken people on the left and the right.

Many Americans have condemned the attacks. But some have not. The biggest divide in support for political violence may not be ideological, but generational, ongoing research suggests.

A survey of more than 4,100 people conducted last year by a California State Long Beach professor found that 93% of baby boomers and 86% of Generation X members say violence is never acceptable to stop political speech, even the most offensive speech. But only 71% of millennials and 58% of Generation Z agreed.

“The wrong conclusion to draw, of course, is that millions of young people are celebrating acts of political violence,” said Kevin Wallsten, a professor of political science who led the survey.

RELATED: The data doesn’t back up Trump’s claims that the left is more violent

“But we should still be concerned,” he said. “Everybody can feel the political temperature rising, and we are being pulled in different directions as a country. We collectively need to think of ways of addressing the deep disaffection that is underneath it.”

Wallsten said leaders at universities, the media and politicians need to “turn down the temperature” by emphasizing that democracy depends on listening to other viewpoints.

“Partisans follow their leaders,” he said. “If you have an unambiguous and widely repeated message that speech is not violence and the appropriate response to offensive speech is more speech, that can start to move the needle.”

Wallsten’s survey, which is part of an ongoing study and will form the basis of a book he is writing, found the same results for young people (age 18 to 26) who are conservative and liberal. And there was little difference between those not enrolled in universities and those who are in college — where Gaza protests and other battles over speech, including during appearances by Kirk and other conservative speakers at California universities — have roiled campuses.

“Charlie Kirk came to our campus in the spring,” he said. “My students were there. One of them said, ‘We should just punch everybody who is in attendance.’ It was a real moment of reflection for me. I thought something has really changed.”

Other surveys have shown similar age-related differences.

A Reuters poll in December found 41% of people aged 18 to 29 said the killing of United Healthcare CEO Brian Thompson was “acceptable” or “somewhat acceptable,” while only 9% of people 60 to 69 did. Luigi Mangione, 27, the man charged with killing Thompson, whose company has faced criticism for denying coverage, became something of a folk hero in some TikTok videos, and supporters have appeared outside his trial.

The man charged with killing Kirk, allegedly over his conservative viewpoints, is 22, and Trump’s slain would-be assassin in Pennsylvania was 20. But those charged in a second Trump assassination attempt and the Hortman and Pelosi attacks were in their 40s and 50s.

One hopeful note, said Dr. Garen Wintemute, director of the Centers for Violence Prevention at UC Davis, is that although his surveys have shown similar trends where more young people than older people voice general support for political violence, only about 2% to 3% say they would consider personally acting on it.

Wintemute said such attitudes have likely always been around.

“Look at all the videos from the 1960s,” he said. “There aren’t a lot of old people throwing Molotov cocktails in those videos.”

Wintemute remembered a protest when he was a student at Yale in 1970 over the Vietnam War and Black Panther leader Bobby Seale’s prosecution, which had National Guard troops with fixed bayonets clashing with his classmates.

“I still have the tear gas canister that I found outside my dorm window,” he said.

“Young people are less patient; they want to see answers quickly,” said Wintemute, who also is an emergency room doctor. “They are passionate. They have less to lose in terms of jobs and families and homes. Many haven’t learned the importance of gradualism and that change doesn’t often happen overnight. All young people learn that. I certainly did. None of that is unique to this moment. It is part of growing up.”

Wintemute said social media worsens polarization. He said Trump should try and heal the country, similar to the way former President George W. Bush attended a mosque after the 9-11 attacks.

“We have a president who famously said of protesters, ‘Can’t we just shoot them in the legs?’” he said. “What leaders say matters. We have a president whose rhetoric encourages violence. There is concern that things may continue to accelerate.”

The current generation has two major differences with prior generations: social media and COVID.

During the COVID pandemic, many young people came of age isolated, noted Wallsten of CSU Long Beach. They faced traumatic events, from the killing of George Floyd by police to the Jan. 6, 2021, attack on the U.S. Capitol by a mob loyal to Trump. A trend in classrooms by some instructors to embrace identity politics in recent years encouraged “safe spaces” and punished “micro-aggressions.” Too often, verbal disagreements have been compared to actual violence, he said, reducing tolerance for other viewpoints.

Social media has amplified and spread misinformation and division, Wallsten added.

“Algorithms feed people a steady diet of content designed to infuriate them and emotionally activate them,” he said. “It is an echo chamber and has a siloing effect. Influencers build their audience by being outrageous.”

Some leaders have attempted to turn down the heat after Kirk’s killing on Sept. 10 at Utah Valley University.

At a discussion at USC on Monday, former California Gov. Arnold Schwarzenegger urged college Republicans and college Democrats to find some issues they can agree on and work together.

“You would be an example for the nation and other universities, how you get together, and don’t see the other side as the enemy, or ‘fight fire with fire’ or declare war on each other,” the former governor said. “You can show leadership, and get together and set an example.”

Kirk’s killing shook many college students in California.

Josue Salvador, a civil engineering major at San Francisco State, where Kirk visited in May, said he agreed with some of Kirk’s views and disagreed with others. He said he was troubled after his death to see some students celebrating.

“I remember seeing a video of him saying that he encourages people with different opinions to speak to each other,” he said. “In friendships, if you don’t speak, you start separating. In a marriage, if you don’t speak, divorce happens. And in a nation, if you’re not speaking, then that can lead to worse things.”

Bay Area News Group reporter Ethan Varian contributed to this report.

Binoculars in hand, dedicated fire spotters scanned the landscape for smoke and radioed firefighters before flames grew out of control. But now, as California enters what is historically the most dangerous part of fire season — the end of summer before the first major rains — lone human sentries have largely given way to a new type of fire lookout on mountain tops: high-tech cameras.

What began as a small research project at UC San Diego 25 years ago has grown into a powerful network of 1,211 cameras constructed on peaks and hilltops across the state with millions of dollars in state funding and oversight from Cal Fire.

Built on towers, observatories and buildings, the cameras are part of a system called ALERTCalifornia. They turn 360 degrees every 2 minutes, taking 12 photos with each pass, 24 hours a day. Upgraded with artificial intelligence software two years ago, they can pan, tilt, zoom, detect smoke and alert fire dispatchers automatically — sometimes before humans call 911.

Each can see 60 miles away on a clear day, and with near-infrared technology, gaze out 120 miles on a clear night.

“Lookouts get up in the morning and work until dusk. But this is 24-7,” said Brian York, deputy chief for fire intelligence at Cal Fire.

“We measure success in all the times that we respond and put out the fires that you never hear about,” he said. “Especially in rural areas at night when most people are sleeping.”

Since 2019, the number of cameras has more than doubled.

The AI lookouts are now on top of many of California’s most prominent peaks, including Mount Hamilton, Mount Diablo and Mount Tamalpais in the Bay Area, Martis Peak at Lake Tahoe, Mammoth Mountain in the Sierra, and the slopes of Mount Shasta.

The cameras have been used to monitor atmospheric river storms, the recovery of California condors, even a tsunami warning along California’s coast in July after an 8.8 magnitude earthquake off Russia. They can be found on Southern California peaks like Mount Wilson near Los Angeles, Cowles Mountain in San Diego, and even on Catalina Island, along with the top of the Dream Inn in Santa Cruz and the roof of the Oakland Coliseum.

Anyone can view the camera feeds live at alertcalifornia.org.

“They are here to help during emergencies,” said Caitlin Scully, UC San Diego spokeswoman. “But they are used all the time by so many different groups. Because they are available for free, people use them to watch big storms, or even check the conditions up in the Sierra when they want to go for a hike.”

The network is based at UC San Diego’s Jacobs School of Engineering, the Qualcomm Institute and the Scripps Institution of Oceanography. It is run and maintained by UC San Diego, with Cal Fire, large utilities like PG&E, Southern California Edison, San Diego Gas & Electric and other partners contributing locations and camera equipment.

From 2019 to 2024, Cal Fire contributed at least $24 million to expanding the system.

New fire departments and other agencies sign up to be partners, and their officials are given access to pan and zoom in the cameras. Last month, East Bay Regional Park District, which has 126,809 acres of parkland across 73 parks in Alameda and Contra Costa counties, signed on.

The network isn’t without its shortcomings.

To address privacy concerns, UC San Diego blurs homes, parking lots and other nearby features that could track people in real time.

The AI system, developed by a DigitalPath, a Chico company, also can’t always tell smoke from dust storms, clouds or other false positives. Its software had to be taught not to report steam from the Geysers geothermal fields in Sonoma County. And in big urban fires, like in Los Angeles in January, residents with cell phones report fires almost as soon as they begin.

“The biggest advantage with them is that we can monitor fires now as they are ongoing,” said Craig Clements, director of the Fire Weather Lab at San Jose State University. “There are limitations with detection. The cameras can see smoke and sometimes hot spots. They can’t see through mountains. And if a fire starts at the bottom of a canyon, you aren’t going to see it. AI and smoke detection are still in their infancy.”

Clements said the technology also may be overtaken in the years ahead by high-tech satellites.

But for now, he said, it is very useful for fire commanders, meteorologists and researchers to learn about fire behavior in real time as huge fires are exploding across the landscape.

“I look at it all the time,” Clements said. “You can’t get flame heights, spread rates and things like that. But I look at the plume structure, how thick the smoke plume is — things you can’t see on satellite. That shows you the state of the fire, and gives you a sense of the fire’s intensity.”

The cameras don’t dispatch fire engines, helicopters or airplanes on their own.

They send a message to dispatch centers across the state, which is then verified by humans.

Last year, there were 7,553 wildfires in Cal Fire’s jurisdiction. Of those, 1,668 were picked up by the cameras, said Cal Fire’s York. And 38%, or 636, were detected by the cameras before any person called 911 to report them.

In one such case on July 6, an AI camera posted an alert at 2:33 am of a fire near Auburn, in the foothills east of Sacramento. Nobody had called 911. Cal Fire’s Grass Valley Emergency Command Center verified it and sent engines. Fire crews found a fire and put it out before it spread beyond a 30 x 30 foot area.

“It was a perfect example of a fire that doesn’t gain attention because it was detected early and extinguished while still small,” York said.

Fire lookout towers with human fire spotters are going the way of the phone booth and fax machine. Where there were once more than 600 in the 1940s, 50s and 60s, today there are only 217 left in California, according to Forest Fire Lookout Association. Only about 50 of the sites are regularly staffed now, mostly with volunteers.

Cell phones, automated cameras, more airplane flights and more people living in rural areas have reduced their effectiveness.

Jamey Erikson, superintendent at Lick Observatory atop Mount Hamilton in the hills east of San Jose, said old paper directions are still posted in offices there telling people how to report the coordinates of fires. But the three ALERTCalifornia cameras at the observatory have made that largely obsolete, he said.

“I use the cameras religiously to look for smoke, to check the weather,” he said. “They are essential.”

The annual Perseid meteor shower, which NASA has called the best meteor shower of the year — and which inspired John Denver to write “Rocky Mountain High” more than 50 years ago — is underway now. It’s expected to peak Tuesday night into early Wednesday morning.

The astronomical show often generates as many as 50 to 75 shooting stars per hour over California and much of the United States. This year, however, the view will be limited by a nearly-full moon on the peak night.

“You’ll still be able to see meteors,” said Ben Burress, staff astronomer at Chabot Space & Science Center in the Oakland Hills. “You might miss some of the fainter meteors, but the moon is not going to overpower the major meteors of the shower. It’s nice to have a very dark sky. But if your goal is to see a meteor, this is a good time, moon or no moon.”

The “shooting stars” that zip across the night sky during the Perseid shower aren’t really stars. They are space pebbles.

The meteor shower occurs every year between mid-July and mid-August when Earth, as it orbits around the sun, crosses a trail of dust and dirt from the famous Swift-Tuttle comet, which itself orbits the sun once every 133 years. The comet is just a huge ball of ice, with rocks, dust and other debris inside it. With each pass around the sun, some of that debris breaks away, and is left behind in the comet’s wake, creating a giant oval that extends from beyond Pluto to around the sun.

As Earth passes through that debris field each year, some of those tiny bits of sand, metal and rock burn up when they come into Earth’s atmosphere, creating the flashing trails we see across the night sky.

“It’s like a car driving into a cloud of insects,” Burress said.

The best time to see the Perseid meteor shower this year will be early in the morning Wednesday, a few hours before the sun rises at 6:23 a.m., said Andrew Fraknoi, chairman emeritus of the Astronomy Department at Foothill College.

You can look for them anywhere in the sky. But the view is best out in the country.

“Get away from city lights and find a location that’s relatively dark,” Fraknoi said.

Be patient, he advised. It takes a few minutes for your eyes to adjust to the dark. And don’t use a telescope or binoculars — they restrict your view and it’s important to see the whole sky to have the best chance at seeing shooting stars.

If you can drive to a dark rural location, like a road or park in the hills around the Bay Area away from city lights and fog, you’ll have a better chance of seeing more meteors.

Chabot Space & Science Center will open its observation deck to the public for a watch party from 11 p.m. Tuesday until 3 a.m. Wednesday, with experts on hand to explain the show. Cost of admission is $15 for adults and $7 for kids.

The Perseid meteor shower was first documented by Chinese astronomers in 36 A.D.

Apart from inspiring people about nature and space for hundreds of generations, the Perseids also inspired a famous song. In 1971, singer John Denver and several friends took a camping trip to Williams Lake, near Aspen, Colorado, to watch the Perseids. Denver, then 27, was so moved he wrote “Rocky Mountain High,” which became a smash hit for lyrics like “I’ve seen it raining fire in the sky” and “shadow from the starlight is softer than a lullaby.”

“Imagine a moonless night in the Rockies in the dead of summer and you have it,” he wrote later in his autobiography. “I had insisted to everybody that it was going to be a glorious display.”

Denver died in 1997 after a light plane he was piloting crashed into Monterey Bay. Ten years later, state legislators named his Perseid-inspired ballad one of Colorado’s two official state songs.

“Even though this kind of event requires you to get up early or stay up late, people are never disappointed,” Burress said. “It’s a good reminder to slow down and smell the roses and decouple from our busy lives and take a moment to observe nature. This is an opportunity to observe something special.”

But one common fixture has been in short supply in recent years: campers.

That’s about to change. The largest campground in Yosemite National Park — and one of the largest at any national park in the United States — is reopening after being closed for three years for a major upgrade.

Workers have finished construction on a $26.2 million renovation of Tuolumne Meadows Campground. It is set to reopen Aug. 1.

Located at 8,600 feet along Tioga Road more than an hour’s drive from Yosemite Valley, the campground has 336 campsites that serve more than 140,000 visitors a year, offering a key starting point where generations of hikers and backpackers have set out to explore Yosemite’s wilderness of sub-alpine meadows, Ponderosa pine forests and scenic granite peaks.

The campground originally was built in 1934 by President Franklin Roosevelt’s Civilian Conservation Corps. Back then, the goal was to stop people from parking randomly in the fragile meadows. The facilities they built created countless vacation memories over the decades. But time took its toll.

“This is a well-loved campground,” said Kathleen Morse, Yosemite’s chief of strategic planning during a recent visit.

“It has a historic and more rustic atmosphere than Yosemite Valley,” she said. “But it was getting pretty dilapidated. Drainage was poor. Sites weren’t level. It was a free-for-all with parking.”

Crews rebuilt the campground’s aging water and sewer systems. They upgraded electrical equipment, and replaced every picnic table, fire ring and food locker at 336 campsites. They renovated the outdoor amphitheater, repaved the access road, added disabled parking spaces, and moved 21 sites out of the floodplain of the Tuolumne River.

“Yosemite gets 4 million visitors a year,” Morse said. “That’s hard on infrastructure. We want to protect the natural resources so they are here forever, and provide a good visitor experience. This is a crown jewel park. We want to have crown jewel facilities that the public can be proud of.”

The Tuolumne Meadows Campground is more than a stop on one of the most famous mountain roads in the American West. It’s also a critical access point for the public.

With campsites for cars, groups and walk-in users, Tuolumne Meadows makes up nearly one-fourth of the roughly 1,500 campsites in all of Yosemite National Park. It has been closed since 2022 for the construction, which could only take place in summer months because the area is buried in up to 6 feet of snow during winter.

Last week, a few early visitors wandered in to see its rebirth.

“This is one of the nicer places we’ve seen on our trip,” said Kevin Thurston, who was visiting with his wife and two sons from Houston. “If we lived closer we’d come up here more. Definitely thumbs up.”

Nearby, Meg Henry, visiting with her husband, Bill Henry, and their two nieces from Los Osos in San Luis Obispo County, remembered how the old campground had aging facilities and a scattershot parking system.

“There used to be cars everywhere,” Meg said. “Instead of cars you see nature.”

Campsites at Tuolumne Meadows are $36 a night. Reservations for all Yosemite hotels and campgrounds can be made at recreation.gov.

The upgrade is the latest in a series of major renovations at Yosemite in recent years. Last year, the park built a new $12.5 million visitor center in the heart of the valley near the Village Store, and completed a $19 million renovation of the trails, restrooms, parking lots, signs and wooden boardwalks around Bridalveil Fall.

This month, crews broke ground on a $220 million project to rebuild the park’s 45-year-old wastewater treatment plant at El Portal.

The money for the Tuolumne Meadows Campground, the El Portal upgrades and several other key projects came from the Great American Outdoors Act. That law, signed by President Trump during his first term in 2020, provided $6.5 billion in new funding to the National Park Service and $3 billion to the U.S. Forest Service, Fish and Wildlife Service and other federal lands agencies to upgrade long-overdue maintenance projects.

Republicans who have in recent years voted against similar environmental efforts embraced the bill after two Western senators, Cory Gardner, R-Colorado, and Steve Daines, R-Montana, were up for re-election in 2020 and urged the White House to embrace a major parks bill they were supporting to help their chances. Daines ended up winning his election. Gardener lost to Democrat John Hickenlooper.

The money, however, continues to fund projects across the United States and the West. In California, it has paid to rebuild water lines at Sequoia-Kings Canyon National Park, upgrade a wastewater system at Furnace Creek in Death Valley, and repave roads and build a new drainage system at Yosemite’s Glacier Point.

Frank Dean, a ranger at Yosemite from 1990 to 1995, also served for 10 years as president of the Yosemite Conservancy, a nonprofit group in San Francisco that has raised private donations to fund hundreds of projects to improve the park’s facilities and restore its environment.

Dean said that although Yosemite Valley receives most of the attention and visitors, Tuolumne Meadows and the park’s higher elevations are singularly beautiful.

“Yosemite Valley is incredible,” Dean said. “Everyone should be able to see it at least once in their life. But to get into the heart of the park’s high country is really special. If you haven’t been up there, you should go. The meadows are flat. You can walk along the river. You can see iconic peaks. It’s an amazing place and it is easy to get to. It’s very special up there.”

It isn’t really getting much better. Or much worse, despite relentless efforts to improve it. And scientists aren’t sure why.

A new study published Monday by researchers at UC Davis shows that the annual average clarity for Lake Tahoe’s azure blue waters in 2024 was 62.3 feet, measured as the depth to which a 10-inch white disk, called a Secchi disk, remains visible when lowered into the water. That’s slightly worse than the previous year’s average of 68.2 feet. But over the past 20 years, the clarity — widely considered a measure of the lake’s overall health — has moved up and down by a few feet a year but generally remained stable.

“We should celebrate the success that we’ve had that has slowed and possibly halted the declines in clarity,” said Stephanie Hampton, director of the UC Davis Tahoe Environmental Research Center. “But why isn’t it getting any better?”

There are some clear trend lines, she noted. The lake is getting more clear in the winter. And less clear in the summer. But numerous new questions remain, including how the lake’s waters, which are slowly warming as the climate warms, may be becoming more favorable to algae growth. Or what role ash and other particles from large wildfires are playing. Or whether microscopic pieces of plastic may be playing a role.

“Lake Tahoe is truly magnificent,” Harmon said. “It is jaw-dropping and beautiful. We want to make it healthier and reverse the declines.”

At 1,645 feet deep, Lake Tahoe is the second deepest lake in America, behind only Crater Lake in Oregon, which is 1,949 feet deep. Over the past half century, the lake’s clarity has become a rallying cry, not just for environmentalists, but also for the business community, which depends on tourism, the linchpin of the region’s economy.

In 1968, the circular disk the size of a dinner plate that UC Davis researchers use to measure visibility in Tahoe’s waters could be seen 102.4 feet below the surface.

After decades of decline when it fell to 85 feet by 1975, then 79 feet by 1985, federal, state and local officials launched a massive effort starting in 1997 to cut the amount of sand, dirt and other sediments flowing into the lake from roads, construction sites and other sources.

Since then, officials have rebuilt stormwater systems around the lake to capture sediment so it doesn’t flow into the water, required developers to reduce erosion, built bike lanes and expanded bus service to reduce traffic — because vehicle exhaust contains nitrogen which can boost algae in the lake — and have thinned more than 90,000 acres of forests in the Tahoe Basin to reduce fire danger.

Between 2004 and 2023, the amount of sediment going into the lake fell by 30%, a drop of about 535,000 pounds a year, said Jeff Cowan, a spokesman for the Tahoe Regional Planning Agency, a government organization established by Congress to regulate development in the Tahoe area.

Similarly, the amount of nitrogen fell 18% and phosphorus fell 20% over the same time, he said.

Now that the decline in clarity has leveled off but not improved, scientists and policymakers say they want to go back and study the tiny particles in the water more closely to better understand where they are coming from and how they are affecting the lake’s clarity.

“We want to know if we are doing the wrong things or not doing enough of the right things,” Cowan said.

The lake seems to become clearer during droughts, when less water carrying sediment and nutrients flows into it. In wet years, particularly after wildfires have burned parts of the landscape, more water flows in, and clarity drops.

For generations, people have wondered if the lake is being loved to death. In the 1860s, Mark Twain called Tahoe “the fairest picture the whole earth affords.” But loggers clear-cut many of the trees around it to provide supports for silver mines in Nevada.

Steady development that began in the 1920s accelerated in the 1950s, with casinos, Frank Sinatra, Marilyn Monroe and the Kennedys joining millions of visitors. Tahoe’s waters started getting murkier because of erosion from construction, fertilizer from golf courses, and loss of wetlands that filter pollutants and other human disruptions.

In the 1990s, former Sen. Dianne Feinstein of California and Harry Reid of Nevada led efforts to hold an annual summit at the lake and expand funding for wetlands restoration, forest thinning and other projects.

Local and state officials set a goal in 2010 to get the lake’s clarity back to 97 feet by the 2060s.

Among the key questions now are learning more about what causes the lake to periodically mix in a major way, when cold clear deep waters move to the surface; trends of different types of organisms, from shrimp to plankton; along with the temperature change. The average temperatures of Tahoe’s surface waters has risen 3 degrees since 1968, up from 50 degrees then to 53 degrees now.

“We need to dig deeper and learn more about the processes and interactions going on below and above the surface,” said Darcie Goodman Collins, CEO of Keep Tahoe Blue, an environmental group. “What role do algae and phytoplankton play in clarity? What role does wildfire smoke and ash play? What about the effects of microplastic pollution and aquatic invasive species?”

“These are questions that don’t have easy or fast answers,” she added. “But anyone who has ever experienced Tahoe knows the effort is worth it.”

But one thing is different this year: Uncertainty. Lots of it. With only two months until the peak visitor season begins at one of America’s most popular national parks, the Trump administration has not announced whether visitors will be required to have reservations to enter, creating confusion.

Last year, in an attempt to cut down on traffic gridlock and overcrowding during busy summer weekends, Yosemite officials required that visitors obtain an entrance reservation for their vehicles between April and October. A similar system was in place from 2020 to 2022 during the COVID pandemic.

Environmentalists generally praised the system. Some businesses opposed it.

But now the Trump administration isn’t telling park officials whether to put it in place again this summer. Travelers from around the world and across the nation are calling hotels in gateway communities, saying they aren’t sure they want to book a vacation if they don’t know whether they will be able to get into the park.

“It’s difficult. Nobody knows,” said Jessie Fischer, whose family owns Yosemite View Lodge and Cedar Lodge Yosemite, on the park’s western edges. “We all wish we could give our travelers peace of mind. We know how difficult it is to plan a trip. If people were planning to go to Disneyland, and they didn’t know if they could get in, not many people would go.”

Park officials aren’t talking. They are awaiting word from Washington, D.C. Yosemite Superintendent Cicely Muldoon retired in February and hasn’t been replaced.

The park’s website says: “Yosemite National Park anticipates sharing details about this year’s reservation system early in 2025. We recognize the importance of providing clarity on that system as soon as possible to accommodate peak summer season travel planning.”

U.S. Sen. Alex Padilla, D-California, sent a letter March 11 to Interior Secretary Doug Burgum asking for a decision, and urging him to continue last summer’s system.

“The uncertainty surrounding the plan’s approval is directly affecting visitors who are trying to make their summer plans now, as well as gateway businesses who depend on summer tourism to survive,” Padilla wrote.

On Friday Padilla’s staff said he hadn’t received a reply.

Asked about the letter and the Trump administration’s summer plans for Yosemite, Jennifer Peace, a spokeswoman for the Department of Interior said via email: “While we do not comment on congressional correspondence, the Department of the Interior takes all correspondence from Congress seriously and carefully reviews each matter. Should there be any updates on this topic, we will provide further information at the appropriate time.”

She did not respond to additional questions.

Rep. Tom McClintock, R-Modesto, whose district includes Yosemite, said he has asked Trump officials not to impose a reservation system this year.

“I expressed my opposition to continuing the reservation system to the administration last month,” McClintock said. “And the sooner it is scrapped, the better.”

McClintock has been a longtime opponent of entrance reservations at Yosemite.

“It might be convenient for the park staff to discourage visitors,” he said. “But it is devastating to the surrounding gateway communities that rely on tourism for their livelihoods. I am confident that new management at the park will adopt a more visitor-friendly attitude.”

Last year, visitors from who didn’t have reservations at a campground or hotel in the park between April and October were required to book a reservation for their vehicle on recreation.gov. If visitors came before 5 a.m. or after 4 p.m., they didn’t need one.

Yosemite dropped reservations in 2023. The park reported waits of 2 hours or longer to get in on busy summer weekends with traffic jams and full parking lots.

“With reservations, you can still welcome the same amount of people, but with the certainty of getting in — without getting stuck in traffic for hours and having overcrowded facilities,” said Neal Desai, regional director of the National Parks Conservation Association, an environmental group. “It basic. You are spreading people out throughout the day, and the week and the month during the busy season.”

Desai noted that 4.1 million people visited Yosemite last year, up slightly from 3.8 million in 2023 when there wasn’t a day-use reservation system.

Last month, the Trump administration fired roughly 1,000 of the National Park Service’s 20,000 employees, including 10 at Yosemite, to cut costs. The park was slow to hire summer seasonal workers due to a hiring freeze Trump imposed after taking office. On Friday, Yosemite announced more summer campground reservations will be offered for sale after recent delays.

Several other big national parks are using a day-use reservation system this summer, including Rocky Mountain in Colorado, Arches in Utah and Glacier in Montana. National parks officials approved those plans before Trump took office.

In Yosemite, park planners held public meetings and drew up hundreds of pages of plans. They completed the process in August and sent the materials to national parks leaders in Washington for final approval. But the plans weren’t acted on before President Biden’s term expired in January.

Some local residents say at this point, they just want clarity one way or the other.

“Bookings are down. People don’t know,” Mariposa County Supervisor Rosemarie Smallcombe. “You have a spouse and two kids and you are trying to plan your vacation. Is there going to be a reservation system? How do I make a reservation? It’s creating a lot of uncertainty, which is having implications for our tourism economy.”

The Republican National Convention starts in three weeks, on July 15. And the first major event of the general election campaign — a high-stakes debate between President Joe Biden and former President Donald Trump — is set for Thursday.

Polls show the race is very close. Audiences for previous debates have been huge. The country is polarized.

A wildcard is Trump’s conviction last month by a New York jury on 34 felony counts for falsifying business records in a scheme to pay hush money before the 2016 election to a porn actress who said they had an affair. And with the two oldest candidates in U.S. history squaring off — Trump is 78 and Biden is 81 — experts say slip-ups or stumbles could play a greater role than in the past.

“A lot of this is going to be about appearance, not the criteria by which high school debates are judged,” said Jack Pitney, a political science professor at Claremont McKenna College. “And I say this having judged many high school debates.”

Many experts expect it to be a more like a brawl.

“I’m looking forward to it. I’ll have my hazmat suit on,” said Larry Gerston, a professor emeritus of political science at San Jose State University.

When is the debate?

The first presidential debate of the 2024 election, and the first time Trump and Biden have squared off on the same stage in four years, is scheduled for 9 p.m. EST/6 p.m. PST Thursday.

Where is the debate?

The 90-minute event will be held at CNN studios in Atlanta. The moderators will be Dana Bash and Jake Tapper. Bash, 53, is host of Inside Politics and co-anchor of State of the Union, both programs on CNN. Tapper, 55, is CNN’s lead Washington anchor and co-host of State of the Union.

How can I watch it?

The debate will be broadcast live on CNN, along with CNN International and CNN en Español. CNN is allowing other networks to air it live if they use CNN’s logo on the screen. ABC, CBS, NBC, PBS, Fox News, Univision, NewsNation, C-SPAN and others have agreed.

What if I don’t have a TV?

Viewers also can watch on CNN.com, NPR.org, YouTube or the streaming platform Max on their computers, tablets or phones.

Will other candidates, like Robert Kennedy Jr., be there?

No. To participate in the debate, CNN required candidates from all political parties to have qualified to appear on enough state ballots to win at least the 270 electoral votes necessary to win the election, and to have reached at least 15% in four national polls. Although he has met the 15% threshold in three national polls that CNN recognizes, independent Robert F. Kennedy Jr. has so far turned in enough verified signatures to qualify for the ballot in only six states — California, Michigan, Hawaii, Oklahoma, Tennessee and Utah — far short of the 270 needed.

Other third-party candidates, including Jill Stein of the Green Party, Libertarian Chase Oliver and independent Cornel West, have failed to meet the thresholds.

What are the ground rules?

Trump was criticized during the two debates in 2020 for repeatedly interrupting Biden, and talking over the moderators.

Neither candidate is allowed to bring notes to the stage, although they can bring a pen, notepad and water. There will be two commercial breaks. During those, the candidates cannot meet with their advisors or staff.

Biden won a coin toss was held before the debate, allowing him to select whether to speak last, or pick a podium. He chose the podium on the right side of the screen. Experts say viewers tend to be drawn more to figures on the right side of stages, which is why nearly all late night TV hosts sit on the right side. Trump chose to speak last as the debate winds up.

What issues are likely to come up?

Experts expect Trump to attack Biden on immigration, border security, crime and inflation, while Biden is likely to talk about record-low U.S. unemployment, his support for restoring abortion rights after Trump’s Supreme Court nominees overturned Roe v. Wade, and the need to preserve American democracy following the Jan. 6, 2021 attack on the U.S. Capitol by Trump supporters.

Wildcards include whether Trump will go after Biden’s son, Hunter, who was convicted of three felonies earlier this month for lying about his former drug use when he purchased a gun in 2018; or how much Biden will hammer Trump for being the first former president in history convicted of felonies.

Both will try to portray the other as corrupt and addled.

“Trump’s followers are only about one third of the electorate,” Gerston said. “He needs independents and people in the middle. He has to go beyond his core. He will try to say Biden has been a failure. Biden needs them also. He’ll say ‘Do you really want Trump back? You fired him. Remember last time? Remember COVID?’”

How many people will watch?

In their first debate in 2020, an estimated 73.1 million people tuned in. That wasn’t as many as the 84 million who watched the first debate between Trump and Hillary Clinton in 2016. But it was the largest TV audience of the year, other than the Super Bowl. This year’s Super Bowl drew 123 million viewers. Also, Thursday’s debate highlights will be shown millions of times in social media clips afterward.

“A win for Biden is getting through the debate without any stumbles,” Pitney said. “A win for Trump would be a Biden stumble.”

When’s the next presidential debate?

The only other scheduled debate is set to be hosted by ABC on Sept. 10. David Muir and Linsey Davis will moderate.

The best places in the country to watch the rare cosmic show — when the moon will pass between the sun and the Earth, completely blocking the sun for about 4 minutes — will be in a 115-mile wide strip stretching through 15 states from Texas to Maine.

If you aren’t traveling to see the full spectacle, NASA has you covered. The space agency will broadcast the total eclipse live, from 10 a.m. to 1 p.m. Monday, Pacific Daylight Time, on its YouTube channel, providing provide telescope views from several sites along the “path of totality,” along with expert commentary. Watch it here:

To watch the eclipse, you must wear special eclipse glasses to protect your eyes. Looking at an eclipse can cause permanent damage to your retinas. If you don’t have eclipse glasses, you can project the eclipse image. Take two sheets of paper, or a stiff notecard, and use a thumbtack to poke a smooth round hole in the middle.

During the eclipse, turn your back to the sun, hold the paper up over your shoulder, and the solar image will be projected onto the ground or other surface nearby. The same thing can be done by holding up a kitchen colander, and projecting dozens of images at the same time through its tiny holes.

To find out what the eclipse will look like and when it will happen in any community, go to: www.timeanddate.com/eclipse/solar/2024-april-8 and enter your town into the box at the upper right.

According to NASA, 20% of the sun’s area will be obscured if you are in Seattle; 22% in Portland; 34% in San Francisco and Oakland; 36% in San Jose; 48% in Los Angeles and 54% in San Diego.

Yet in a run of much-needed good fortune, California has been spared this year — at least so far.

There are still at least two months left in fire season, and hot weather is forecast over the next two weeks, so things could change. But as of this week, fewer acres have burned in California this year than in any year since 1998, according to an analysis of 25 years of federal and state fire records by this news organization.

“It’s been great. We don’t want to see fire. We don’t want to see anybody hurt,” said Scott McLean, deputy chief of Cal Fire, the state’s primary firefighting agency. “Our troops need the break. They need the rest.”

From Jan. 1 through Aug. 21, a total of 65,360 acres burned statewide on all types of land, including private property, national forests, national parks and other lands. That’s a staggering 94% less than what had burned last year over the same period in California: 1,096,033 acres, an area more than three times the size of Los Angeles.

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More noteworthy: This year’s total is 83% lower than the previous 10-year average through Aug. 21, which is 387,295 acres.

On Friday, as crews put the finishing touches on extinguishing the 600-acre Mountain fire north of Redding, no major fires were burning anywhere in California. In fact, the U.S. Forest Service has rated most of the state as at “moderate” risk for wildfires this week, issuing a map largely colored green while major parts of Nevada, Utah and Arizona were orange and red.

There are two main reasons for the lack of catastrophic fires this year, experts say.

First, this past winter was very wet across the state. Fed by soaking atmospheric river storms that barreled in off the Pacific Ocean, the Sierra Nevada snow pack grew to 161% of its historical average by April 1. Lake Tahoe filled to the top, and ski resorts stayed open until July.

Fires don’t burn in snow. At lower elevations, umbrellas were out a lot, too. Rains filled reservoirs and replenished rivers and groundwater basins that were still suffering from the state’s five-year drought, which ended in 2017. That drenched millions of acres, reducing fire risk.

Added to that, temperatures across much of California have been slightly cooler than normal so far this summer, even though other parts of the world have seen record heat waves as the climate continues to warm. Record wildfires are raging in Alaska, Siberia and the Amazon rainforest, for example, and last week federal scientists reported that July was the hottest month globally ever recorded back to 1880 when modern temperature records began

“We have epic fires elsewhere,” said Craig Clements, professor of meteorology at San Jose State University and director of the school’s fire lab. “But because our weather locally was cooler and wetter, our fire danger was lower. But in the long term, the trends are showing we are going to have more drought and warmer temperatures. That’s going to affect wildfire.”

A key factor in wildfire risk in California is the moisture content of plants — basically, how much water they have soaked up. The more water they have, the more difficult it is for them to burn.

The moisture content of manzanita and chemise, two plants scientists regularly measure to gauge fire risk across California, is about 20% higher now in the Bay Area than average, Clements said.

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So even though wet winters cause more grass to grow, he said, when larger vegetation like shrubs and trees soak up more moisture during wet winter and spring conditions, fires that start in the grasses don’t spread as rapidly to shrubs and trees as they do in dry years. That allows fire crews to make progress before the flames explode out of control and burn hundreds of homes.

“There have been a lot of ignitions, but the fires are being put out,” Clements said. “They aren’t spreading as fast this year.”

That’s what happened Thursday when an ominous fire began 15 miles north of Redding, near Shasta Lake. That blaze, called the Mountain fire, immediately re-kindled memories of the Carr fre last August, which started when a flat tire on a vehicle caused its metal rim to spark against the road. That fire burned for a month, charring 229,000 acres around Redding, killing three firefighters and five residents, destroying 1,600 buildings and causing $1.6 billion in damage.

As soon as the Mountain fire started, Cal Fire, the Forest Service and local fire agencies leaped into action, sending more than 500 firefighters to the blaze in meadows, rural subdivisions and oak woodlands.

Roughly 4,000 residents in the area near Shasta Lake were evacuated. But by Friday morning, the fire’s progress had halted at 600 acres, and crews said they expected it to be out by late Saturday. Three homes burned, but no one died.

“The concern was that we are looking at triple-digit heat with winds forecast for this week coming up,” said McLean. “We wanted to get ahead of the game. There are no flames there now, just a few hot spots.”

An analysis by this news organization of fire and weather records over the past 25 years shows that four of the five worst fire years back to 1994 all occurred after drier-than-normal winters and, similarly, four of the five mildest fire years, including this year, all occurred after wetter-than-normal winters.

There are exceptions. In late 2016 and early 2017, there was a very wet winter. But dry conditions followed in October, and by November, heavy winds knocked down power lines across the state, sparking fires across Napa, Sonoma and Lake counties.

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With forecasters calling for hot weather over the next two weeks, fire crews are on alert, McLean said, adding that he hopes for rain in October to dramatically cut fire danger.

“We can’t be complacent,” he said. “We still have a long way to go. September and October are historically our worst months for fires. It only takes one spark.”

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(San Jose Mercury News researcher Leigh Poitinger contributed to this report.)

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