BOSTON (AP) – Stubborn clouds and early showers didn’t deter thousands of Fourth of July revelers from crowding the Esplanade Tuesday for fireworks, the 1812 Overture and rock-n-roll Hall of Famers from Aerosmith.

“What could be more iconically American than rock n’ roll?” said Boston Pops conductor Keith Lockhart hours before he shared the stage with Steven Tyler and guitarist Joe Perry. “Arguably, Boston’s two most famous bands are the Pops and Aerosmith.”

Local American Idol finalist 17-year-old Ayla Brown opened the show with “The Star-Spangled Banner.”

“I love being a hometown girl – Boston – that’s why it’s such a thrill to be here tonight,” Brown, wearing a slinky evening dress, said before going onstage.

State police estimated 450,000 to 500,000 people gathered for the concert and 23-minute pyro-musical fireworks extravaganza near the Charles River.

Some held American flags, and others red-white-and blue pompons as they sat on blankets on the grass. People ate kettle corn and barbecue. They devoured plates of fried dough and fried chicken.

Two-year-old Dominic Salamone stood barefoot in the grass playing with a red balloon that had been tied to look like a dog. The balloon burst with a pop and he shrieked with delight. “The fireworks, the fireworks,” he said.

His father Matthew Salamone, 25, picked up his son and tossed him playfully in the air. The Salamone family had come three hours in advance from West Medford to find a good spot for the show.

Ten-year-old Alicia Dumont wore a red-and-blue Statue of Liberty-style crown and a red tank top to the festival. She and her family came from Quincy at 2 p.m. for the show.

“I think it’s awesome,” Alicia said. “It’s spectacular just to celebrate the Fourth of July and see all the colors.”

Among the crowd were performing mimes, some dressed in navy dress whites and others in copper-green Statue of Liberty costumes. Then there was Maurice Ely Jr., 31.

“I’m Space Ghost from the Hanna-Barbera cartoon,” Ely said.

He was wearing a white jumpsuit with a yellow cape and black mask that came past his nose. “It might rain again, so just brace yourself. I’m not worried about it, I’ve got my force field.”

Hundreds of boats dropped anchor in the Charles River, securing a spot to watch the more than 19,000 pounds of fireworks ready to erupt over Boston. The shells, ranging from one to 12 feet in diameter, will be shot from barges to produce more than 10,000 explosions.

The modern celebration dates back to 1974 when the Boston Pops played Tchaikovsky’s 1812 Overture, accompanied by the percussion of blasting fireworks. This year’s nationally televised gala also included television show host Dr. Phil McGraw.

, singing group Rockapella, and Renese King.

The aging rockers from Boston-based Aerosmith headline the show with the Boston Pops at the Hatch Shell. It is the first time that Tyler, 58, and Lawrence-native Perry, 55, have played at the event.

“I had their albums,” said Lockhart, 47, of Aerosmith. “They’re nearing 60 at this point. But they really still perform like their lives depended on it. They eat the stage up.”

Past guest headliners include Cyndi Lauper, David Lee Roth of Van Halen fame, and last year’s country performers, Big & Rich and Gretchen Wilson.

Boston began its Fourth of July celebration Tuesday morning with a reading of the Declaration of Independence from a balcony at the Old State House, where townspeople first heard it two centuries ago, by the Ancient and Honorable Artillery Company.

The USS Constitution, at 208 years old the world’s oldest commissioned warship, made its annual turnaround cruise through the Boston Harbor and returned to berth facing the opposite direction. Aboard the ship, 10 immigrants were sworn in as naturalized citizens.

“I don’t have the words to describe it right now,” said Army Sgt. Denver Benjamin, a native of St. Kitts and Nevis in the Caribbean, who took the citizenship oath. “It’s one of the best feelings of my entire life.”

Across Massachusetts temperatures hovered in the 70s, but lines still formed at ice cream shops. Parades marched between rain drops. In Franklin, a float was dedicated to Marine Lance Cpl. Shayne Cebino, who was killed in Iraq in October at the age of 19.

AP-ES-07-04-06 2120EDT