Hundreds of thousands of people braved record heat yesterday to pitch tents, throw blankets and stake out cooler-crammed patches of the communal front yard that is the National Mall to celebrate Independence Day under a shower of spectacular fireworks.

And, true to the best of this country's ideals, the crowd gathering for the last hurrah of the American Century looked a lot like America itself: all conceivable colors, political persuasions, languages and outfits. There were shimmering saris; tattoos and pierced noses; red, white and blue striped shorts and baseball caps.

From the moment the fireworks first filled the sky with falling stars and crackling waterfalls of blues, greens, purples and yellows, 7-year-old Kelly Krajecki, of Alexandria, was practically speechless.

"Aren't they pretty," her mother Joanne asked.

"Yes," the little girl answered softly. "Wow."

For the Peterson family, who drove 6 1/2 hours from Cleveland for 20 minutes of seeing a starless sky burst into flame and hearing machine-gun-like noise, the favorite was no contest: "the ones that poofed out and looked like huge Koosh balls," said 11-year-old Alyse as her sisters scrambled for the charred bits of firework paper that fell in a rain of ashes.

Some, like Thomas Dodson, of Silver Spring, his wife, Deanna, and their three children, made an annual pilgrimage and arrived on the Mall as early as 9 a.m. to lay claim to the best place to view the burst of fireworks.

"We've been coming for five or six years straight," Thomas Dodson said, sitting on a lawn chair under a shade tree off the Ellipse, sipping a root beer as his children ran off to play soccer. "We try to get this spot every year."

Some simply relished a good party. "It was just one of those things I'd heard about, like Mardi Gras," said Shana Rosenthal, 23, who moved to the Washington area three months ago.

At least during the afternoon, the intense heat wave was keeping the crowds somewhat smaller than usual. But by nightfall, the crowd surged.

"It appears to be fewer people, and there certainly seems to be less traffic because of the heat," said Cmdr. Michael Radzilowski, of the D.C. police special operations division, who led the police mobile command center, an air-conditioned unit perched at 17th and C streets NW. "But they came out when the sun went down."

Many of those who braved the weather came prepared. Tony Mackel, 40, of Gaithersburg, sat yoga-style in a small blue kiddie pool filled with water. He was surrounded with essential American kitsch: a one-foot-high plastic white picket fence, twirling plastic daisies, fake tulips, a plastic pink flamingo and a mailbox with "Second Family" written on it.

For others, like Sridhar Vallepalli, the Mall was "the only place to be" to celebrate the Fourth of July and the idea of America. "This is such an important day for American history," said Vallepalli, who left his native India for a job with Bell Labs in New Jersey.

The crowd at the base of the Washington Monument whooped and hollered and stood in applause as the fireworks ended.

"I'd heard that it was incredible," said Shamit Mehta, 21, of Boston. "It's one of those things you have to do in your lifetime."

Joe Wichie and his family came from Troy, Ohio, just to be on the Mall yesterday. "We thought it would be the most awesome thing," said Helen Wichie, 43. "We spent the night talking to the children about how lucky they are to live in this country and what freedom means."

She pointed to the Washington Monument, encased in its bright blue brick-like scaffolding, and asked her daughter what it stood for. "World War II?" ventured Jessica, 11.

Likewise, John Tibbs, 36, of Washington, spoke to his daughter, Johnesha, 9, about the war in Kosovo before trekking to the Mall for an afternoon spent feasting on hot dogs, hamburgers, barbecued chicken, chips and salad.

"I talked to the kids about freedom," Tibbs said as Johnesha and her sister, Jasmine, 3, cooled off with water guns and cold drinks. "About all the families over there."

In a field near the Lincoln Memorial, activists at the annual Smoke-In, who were promoting everything from medicinal use of marijuana to the use of hemp in clothing, recruited passersby as the smell of marijuana drifted throughout the air. "Usually it's so packed you can't walk around," said organizer Chris Colvin. "There are less people here because of the heat."

The Smoke-In resulted in three of the day's 18 arrests, according to Park Service officials. "There was weed everywhere," said Sgt. Robert MacLean, spokesman for the U.S. Park Police.

Fourteen others were arrested for vending without a permit, and one man was arrested for assaulting his wife with a bottle, police said.

Authorities said 42 people were taken to hospitals for heat-related symptoms.

U.S. Park Police checked coolers and warned visitors not to bring alcoholic beverages onto the Mall, enforcing the three-year-old rule and also guarding against the dehydration that results from drinking alcohol. Last year, Park Police confiscated about 2,400 cans of beer, they said. By late last night, the tally was about 485.

Stephen Lichtman, 34, vice chairman of the Montgomery County First Aid Unit, said yesterday "certainly ranks as one of the hottest I've ever worked." The unit staffed two of the five first-aid tents, where children rested and sponged water on their hair and faces.

Besides the heat, another hallmark of yesterday's holiday was a new Metro plan for moving people in and out of downtown. The transit agency rerouted trains to help ease the bottleneck at the stations nearest the Mall. Last year, it took two hours for the Smithsonian station to clear when 100,000 descended after the fireworks.

Many found the changes confusing. "We ride this train every day, but you need to be a brain surgeon to figure this out today," said Lamika Hines, who boarded at the U Street-Cardozo station and was studying one of the special maps Metro had designed for the day.

Metro officials lined the platforms at several stops, literally shooing muddled people onto the trains. "Yes, this one, the yellow one, go, go, go," said Sylvester Harvey to one man, trying to get from the Pentagon stop to Union Station. "A lot of people look like they are lost."

After the fireworks ended, crowds took to heart Metro's plea to use the L'Enfant Plaza and Archives-Navy Memorial stations, in order to take the pressure off of the Smithsonian stop, Metro officials said. People stuffed themselves by the thousands into those stations, and at 11 p.m., prospective riders at L'Enfant Plaza had waited an hour and 15 minute to navigate their way from the station's entrance to the platform.

In the distance, a lone trumpet played patriotic songs such as "God Bless America," as well as a little jazz and a little blues. People danced, played games and just sprawled on the grass to wait.

Ingrid Moody, 17, danced to the trumpet tunes with some nearby teenagers, but when the muggy air got to her, she flopped down on a blanket and put her head in her mother's lap.

"We're talking about Furbys, and wishing there was a bathroom around here," she said as her mom pushed the hair from her face. "But it's okay. This is nice."

Yesterday's celebrations weren't confined to the Mall. Across the region, people watched puppet shows, marched in homegrown parades, gathered with friends for backyard barbecues, twirled sprinklers or shot off firecrackers.

In Herndon, close to 500 people ate close to 1,500 hot dogs, and children ran three-legged races and competed in a sponge toss at the town's Bready Park. To fight the heat, which organizers estimated cut the crowd in half, Herndon's Parks and Recreation Department purchased more than twice the usual amount of lemonade. "We bought out the entire shelf in the supermarket," said Ron Tillman, 31, of Ashburn, a Parks and Recreation coordinator. "We can't keep the jugs filled fast enough."

"There aren't many towns that celebrate the Fourth of July together," said Seth Watari, 51, of the Herndon Optimist Club, who has been cooking hot dogs at the festival for 16 years. "This really is a piece of small-town Americana."

At a block party in the Midvale neighborhood in Wheaton, Carman Guevara, 33, who arrived in this area from Peru 11 years ago, was celebrating so that her 2-year-old daughter Stephanie would appreciate her U.S. citizenship. "I want her to know all about her country," she said, "and all three of her cultures: Peruvian, Nicaraguan and American."

In Rosslyn, 52 area residents from 49 nations were sworn in as U.S. citizens at an Immigration and Naturalization Service ceremony at Freedom Park.

"I'm excited because it's the last Fourth of July in this century," said Sierra Leone native Elizabeth Pratt-Lewis, 55, of Alexandria, who took the oath of allegiance dressed in traditional garb. "I'll always remember this."

Back on the Mall, Laura Miller, a teacher at the University of Maryland, first said the Fourth of July had lost its meaning--"like Christmas, it's just another day." But as she spoke of the special spot on the west side of the Washington Monument, where the fireworks are so close it seems they fall right on your face, exploding in time with the soaring music from the National Symphony Orchestra, Miller softened.

"There is something about that," Miller said. "It kind of makes your throat catch."

Staff writers Hannah Allam, Marcella Bombardieri, Sewell Chan, Maria Glod, Daniel A. Grech, Tomoko Hosaka, Mary Schumacher and Jamie Stockwell contributed to this report.

CAPTION: Christopher Branton, left, and his parents, Caroline and Sam, watch the annual fireworks display on the mall. At left, Paul Rice, of Silver Spring, plays with his nieces, 3-year-old Jillian Wessel, left, and 2-year-old Rae Wissel, while they wait for the evening concerts and fireworks to begin at Lake Kittamaqundi in Columbia.

CAPTION: Tito Puente performs a sound check in the afternoon before his scheduled performance last night at the Sylvan Theatre near the Washington Monument.