The Purple Line is a 16.2-mile (26.1 km) light rail line being built to link several Maryland suburbs of Washington, D.C.: Bethesda, Silver Spring, College Park, and New Carrollton. Currently slated to open in late 2027, the line will also enable riders to move between the Maryland branches of the Red, Green, and Orange lines of the Washington Metro without riding into central Washington, and between all three lines of the MARC commuter rail system. The project is administered by the Maryland Transit Administration (MTA), an agency of the Maryland Department of Transportation (MDOT), and not the Washington Metropolitan Area Transit Authority (WMATA), which operates Metro.

Bethesda is an unincorporated, census-designated place in southern Montgomery County, Maryland, United States. It is located just northwest of Washington, D.C. According to the 2020 census, the community had a total population of 68,056. It takes its name from a local church, the Bethesda Meeting House, which in turn took its name from Jerusalem's Pool of Bethesda. The National Institutes of Health's main campus and the Walter Reed National Military Medical Center are in Bethesda, in addition to several corporate and government headquarters.