Philadelphia hosted the 1776 Second Continental Congress whose adoption of independence America250 commemorates.
The Congress met primarily at the Pennsylvania State House, now known as Independence Hall. Delegates debated the Lee Resolution, approved the Declaration of Independence, managed the Revolutionary War effort, and coordinated diplomacy for the colonies.
Philadelphia was a major commercial and political center in British North America, making it a practical meeting place for representatives from the thirteen colonies. It remained central to early American national life after independence.
Washington, D.C., was not the capital in 1776; it was not founded as the national capital until later. Boston and New York were important revolutionary cities, but neither hosted the Congress for the adoption of the Declaration.