Baltimore/Washington International Thurgood Marshall Airport (IATA: BWI, ICAO: KBWI, FAA LID: BWI) is an international airport in Anne Arundel County, Maryland, located 9 mi (14 km) south of downtown Baltimore and 30 miles (50 km) northeast of Washington, D.C.

BWI is one of three major airports that serve the Washington–Baltimore metropolitan area. Dulles International Airport (IAD), in Dulles, Virginia, and Ronald Reagan Washington National Airport (DCA), in Crystal City, Virginia, are the other two.

The airport serves as one of 12 U.S.-based operating bases for Southwest Airlines. In 2023, BWI recorded 12,849,636 passenger enplanements, making it the busiest airport in the Baltimore-Washington metropolitan area, ranked at #23 in passenger enplanements in the U.S., followed by Ronald Reagan Washington National Airport (#24) and Washington/Dulles Int'l Airport (#26).

In 2005, the airport was named in honor of Thurgood Marshall, a Baltimore native and the first African American to serve as a U.S. Supreme Court justice.