New York City hosted the major 1976 Operation Sail event during the American Bicentennial.
Operation Sail, often called Op Sail, brought tall ships and naval vessels together for international maritime celebrations. The 1976 event in New York Harbor formed part of the United States Bicentennial observances and drew an exceptionally large fleet from many countries.
The ships sailed into the harbor on July 4, 1976, creating one of the most memorable visual spectacles of the bicentennial. The event was linked to the arrival of visiting vessels and to a large naval review attended by President Gerald Ford.
Philadelphia was the site where the Declaration of Independence was adopted, so it is a plausible alternative in this question. Washington, D.C., was the national capital and hosted many bicentennial programs, but the famous 1976 Operation Sail harbor gathering took place in New York City.