The 1790 Residence Act designated the Potomac River area for the permanent United States capital.
President George Washington signed the Residence Act on July 16, 1790. The law authorized a federal district along the Potomac and gave Washington responsibility for selecting the precise location and supervising the project.
The decision was part of a political compromise involving Alexander Hamilton, Thomas Jefferson, and James Madison. Northern lawmakers gained support for federal assumption of state debts, while southern lawmakers secured agreement to place the capital on the Potomac, closer to the southern states than the temporary capital in New York.
The original federal district was planned as a square of up to ten miles on each side. Land came from Maryland and Virginia, although the Virginia portion was later returned in the nineteenth century. The capital moved temporarily to Philadelphia before the federal government took up residence in Washington in 1800, making the Potomac choice a lasting feature of the American national story.