On July 27, 1789, President George Washington established the Department of Foreign Affairs. It was the first federal agency created under the Constitution of the United States.

The Constitution gave the President the responsibility for the conduct of the nation's foreign relations. It soon became clear, however, that an executive department was necessary to support the President in the conduct of the affairs of the new federal government. In response to this need, Congress approved legislation to establish a Department of Foreign Affairs. President Washington signed the legislation into law on July 27, 1789.

The Department of Foreign Affairs was responsible mainly for foreign relations. These responsibilities grew, however, to include management of the United States Mint, keeping of the Great Seal of the United States, and taking the U.S. census. Thus, the name was changed from Department of Foreign Affairs to Department of State, with the head of the Department called the Secretary of State. President Washington appointed Thomas Jefferson as the first Secretary of State in 1789. Most of the domestic duties of the Department of State were eventually turned over to various new Federal departments and agencies that were established during the 19th century.

The legislation which created the Department of Foreign Affairs still remains the basic law of the Department of State today.