In a New York minute, everything can change. This saying, it seems, holds even more truth on the Fourth of July.

In the course of 60 seconds on Wednesday night, the silent skies will transform into a cacophony of booms as eight barges unleash approximately 1,300 explosives to begin the largest fireworks show in America.

During the next minute, another wave of shells will go up, and they’ll go up every minute thereafter until all 40,000 shells from Macy’s 31st annual Fourth of July fireworks show have exploded in the sky.

For the sake of comparison, a single barge in New York’s fireworks fleet is said to hold more explosives than the entire fireworks show on the National Mall in Washington. During an average 20-minute fireworks show in America, only 500 shells are fired.

“It all goes back to ‘The Star-Spangled Banner,'” the executive producer of the Macy’s fireworks show, Robin Hall, said. “It sort of replicates what it’s like to be in a revolutionary battle for independence: the smoke, the gunpowder, the flash of light. I think all of it is emblematic of the struggle for independence.”

The 30-minute show, which will start at about 9:20 p.m., takes more than a year to plan and features cutting-edge fireworks from around the world.

The president of Souza Fireworks of Rialto, Calif., James Souza, designed the show with his brother, Gary, vice president of the company. The Souzas travel to Spain, Italy, China, and Japan to meet fireworks manufacturers and select surprise additions for each year’s show. The family has been in the fireworks business for five generations and has helped orchestrate the Macy’s show for the past 25 years.

“Each country has its own little flavor. It’s almost like wine,” Gary Souza said. “The colors have become much more vivid.”

This year’s show will feature bursts of fuschia, lemon, lime, and orange blasted in what Gary Souza is calling a “high definition” format.
Much like the wide screens on high-definition televisions, this year’s fireworks scenes will stretch wider than usual, and some colorful explosions will appear to dance just above the water.

The low-lying fireworks, known as water fireworks, are new in America but a century-old tradition in Japan. They’ll create a bright, luminescent glow in the river, Gary Souza said.

The shells are loaded into steel and fiberglass mortars before the show and then wired to a firing system with more than 30,000 feet of wiring. The shells are fired in a carefully choreographed performance set to music performed by the New York Pops, which is broadcast on 1010 WINS.

This year’s accompaniment includes an original song, “In Our Children’s Eyes,” composed by Macy’s creative director, William Schermerhorn and a Tony Award-winning composer, Stephen Flaherty. The fireworks show also can be viewed on NBC at 9 p.m.
The fireworks will spout from eight barges, six of which will be stationed along the East River between 23rd and 42nd streets and the other two near the South Street Seaport. The fireworks can be seen from Manhattan, Brooklyn, and Queens.

The southbound lanes of the FDR Drive between 14th and 42nd streets will be open to the public at 7 p.m. Wednesday for viewing.

To see the fireworks from the South Street Seaport, organizers recommend traveling to the Brooklyn Heights Promenade, the Empire-Fulton Ferry State Park, and Furman Street from Atlantic Avenue to Cadman Plaza West in Brooklyn. In Manhattan, prime spots for spectators include the lower portion of the FDR Drive.

Mr. Hall would not say how much money Macy’s spends on the annual show.

“As with any good gift, you cut off the price tag,” he said. “It’s all about celebration and bringing the nation together.”