The 1790 Residence Act selected a site along the Potomac River for the permanent United States capital.
President George Washington signed the Residence Act on July 16, 1790. The law authorized a federal district on the Potomac and gave the president power to appoint commissioners to oversee its location and development. The site eventually became Washington, D.C.
The decision formed part of the Compromise of 1790, a political agreement involving Thomas Jefferson, James Madison, and Alexander Hamilton. Southern support for assuming state debts helped secure agreement for placing the capital on the Potomac, while Philadelphia served as the temporary capital until the new city was ready.
The Potomac is sometimes confused with the Anacostia River, which flows through the eastern part of Washington, D.C. The Residence Act referred to the broader Potomac site, and Washington later selected the exact location near Georgetown and Alexandria. The federal government moved from Philadelphia to Washington in 1800.