The United States Department of State, often referred to as the State Department, is the Cabinet-level foreign affairs agency of the United States government, similar to foreign ministries, foreign offices, ministries of external relations, etc. in other countries. It is administered by the Secretary of State, the office currently held by Hillary Clinton.

It is headquartered in the Harry S Truman Building at 2201 C Street, N.W., a few blocks from the White House in the Foggy Bottom neighborhood of Washington, D.C. The Department's Secretary is the first Cabinet member in the line of succession in the event of the disability or death of the President, and is fourth after the Vice President, the Speaker of the House, and the President pro tempore of the United States Senate.

The U.S. Constitution, drafted in Philadelphia, Pennsylvania in 1787 and ratified by the states the following year, 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.