New Yorkers will be able to waltz on their rooftops Friday night in step with the theme of this year’s Independence Day fireworks show: “America Dances.”

Digital synchronization, the show’s creative director, Bill Schermerhorn, said, will allow fireworks to move in closer harmony than ever with a live sound track provided by the New York Pops, directed by Rob Fisher. The challenge with every July 4 celebration, Mr. Schermerhorn said, is “finding a way to be very Americana and patriotic. What better way to do that than with the music America has danced to over time?” Macy’s will work with city agencies and sponsors for its 32nd year to stage the cutting-edge musical pyrotechnics display.

New York City’s Independence Day celebration is the largest in the nation, dwarfing the world-class shows in Boston and Washington. “There are more fireworks on one barge than in the show in Washington, D.C.,” the show’s executive producer, Robin Hall, said.

The barges will be positioned along the East River, stretching between 10th and 24th streets, and near the Brooklyn Bridge, parallel to South Street Seaport and the Brooklyn Heights Promenade. They will release more than 35,000 shells, or about 1,100 every minute, beginning at about 9:25 p.m.

The musical lineup includes some unexpected Independence Day fare, beginning with the “Gotta Dance!” fanfare, based on the song Gene Kelly made famous in the 1952 musical “Singin’ in the Rain.” The dance numbers will continue with oldies including “The Twist” and “Good Golly Miss Molly,” and several show tunes: Stephen Flaherty, who arranged the “Getting’ Ready Rag” for the 1998 musical “Ragtime,” wrote a new ending to his piece for this show, Mr. Schermerhorn said.

The Pops will be accompanied by an assortment of popular recording artists, including country music singer Kenny Chesney; pop musicians Gavin DeGraw, Natasha Bedingfield, and Jordin Sparks, and an “American Idol” finalist, Katharine McPhee, who will perform a slow rendition of “Save the Last Dance for Me” as the famous “Golden Mile” fireworks display bursts over her head.

The fireworks barges will be farther down the river than they have been in years past, Mr. Hall said, to allow NBC’s show commentators to broadcast live from Brooklyn with the Manhattan skyline at their backs. But, Mr. Hall said, the view from sanctioned locations, including the FDR Drive, the Brooklyn Heights Promenade, and Empire Fulton Ferry State Park in Brooklyn, will be unaffected. Stacey Sherman, a spokeswoman for the Water Taxi Beach, which offers beach access for the show and a three-hour fireworks cruise package, said the barges’ relocation would not change the “prime views of the fireworks” from the beach.

The FDR Drive will be closed to traffic between Houston and 42nd streets and between Broad Street and the Brooklyn Bridge for public viewing of the show. While the pyrotechnics will be visible from rooftops in Manhattan, Brooklyn, and Queens with views of the East River, the public will not be allowed to watch the show from the Manhattan, Brooklyn, Queensboro, or Williamsburg bridges, or from Battery Park. The New York Pops will be broadcast live on the 1010 WINS New York radio station, and the whole event can be seen live on NBC.

This year, the show’s elite fireworks designer, Gary Souza, whose company, Pyro Spectaculars, has also designed shows for Olympics ceremonies and the 1994 World Cup, has encouraged viewers to watch for a perfectly synchronized music-and-light experience, with lower-altitude explosions that fill the entire sky.

“I think they should expect to see the fireworks more adequately timed to the music,” he said. The audience should “not just look at it for the booms and bangs,” he said, “but pay attention to the pace of the show.”

Mr. Souza’s team gathered the fireworks from exotic locations including Spain, Italy, and East Asia. Nautical fireworks, which hover just above the water as they change colors and transform, will return for a second year. And rectangular shells, a new effect, will shift dimensions and geometric angles in the sky.

But Mr. Souza said he most looked forward to seeing silver lights move to the “Tennessee Waltz,” a more subdued display. Fireworks will form soaring stars and cascading waterfalls; the effect, he said, will be “softer, quieter, and very elegant.”