The Washington Metropolitan Area Transit Authority, commonly referred to as Metro, is a tri-jurisdictional public transit agency that operates transit service in the Washington metropolitan area. WMATA was created by the United States Congress as an interstate compact between Washington, D.C., Maryland, and Virginia.

The Washington metropolitan area, also referred to as the DC area, Greater Washington, the National Capital Region, or locally as the DMV, is the metropolitan area centered around Washington, D.C., the federal capital of the United States. The metropolitan area includes all of Washington, D.C. and parts of Maryland, Virginia, and West Virginia. It is part of the larger Washington–Baltimore combined statistical area, which is the third-largest combined statistical area in the country.