The United States Department of State (DOS), or simply the State Department, is an executive department of the U.S. federal government responsible for the country's foreign policy and relations. Equivalent to the ministry of foreign affairs of other nations, its primary duties are advising the U.S. president on international relations, administering diplomatic missions, negotiating international treaties and agreements, and representing the U.S. at the United Nations. The department is headquartered in the Harry S Truman Building, a few blocks from the White House, in the Foggy Bottom neighborhood of Washington, D.C.; "Foggy Bottom" is thus sometimes used as a metonym.

Established in 1789 as the first administrative arm of the U.S. executive branch, the State Department is considered among the most powerful and prestigious executive agencies. It is headed by the secretary of state, who reports directly to the U.S. president and is a member of the Cabinet. Analogous to a foreign minister, the secretary of state serves as the federal government's chief diplomat and representative abroad, and is the first Cabinet official in the order of precedence and in the presidential line of succession. The position is currently held by Antony Blinken, who was appointed by President Joe Biden and confirmed by the Senate on January 26, 2021, by a vote of 78–22.

As of 2019, the State Department maintains 273 diplomatic posts worldwide, second only to China's Ministry of Foreign Affairs. It also manages the U.S. Foreign Service, provides diplomatic training to U.S. officials and military personnel, exercises partial jurisdiction over immigration, and provides various services to Americans, such as issuing passports and visas, posting foreign travel advisories, and advancing commercial ties abroad. The department administers the oldest U.S. civilian intelligence agency, the Bureau of Intelligence and Research, and maintains a law enforcement arm, the Diplomatic Security Service.