The parachutists seemed to float in the air for a few minutes, then swooped down and landed about 20 feet from the applauding crowd, which had come to take part in Philadelphia's Flag Day celebration.
"I thought they were gonna jump on us!" said Sarah Goldman, 10, there with her family.
The aerial acrobats, a civilian crew from Middletown, Ohio, prepared for their jump by examining satellite photos of the field at the Constitution Center and by visiting the site.
Professional skydiver Paul Stanford, a former Marine sergeant, said the weather and wind were perfect for the jump.
Flag Day doubles as the U.S. Army's birthday, this year being its 238th, and Stanford said that several members of his team are Army veterans.
He was thrilled at the chance to parachute in to Philadelphia with the Stars and Stripes.
"There's no better time to do it than Flag Day," he said. "Who gets to do that?"
Flag Day events took place across the country. In New York, a huge free-flying American flag, one of the world's largest, hung from the George Washington Bridge. And in Montgomery, Texas, military veterans gathered to talk about their service.