Baltimore/Washington International Thurgood Marshall Airport (IATA: BWI, ICAO: KBWI, FAA LID: BWI) – also known as Thurgood Marshall Airport, Baltimore/Washington International Airport, and simply as BWI Airport – 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 2024, BWI ranked second behind Washington/Dulles Int'l Airport in the Baltimore/Washington area with 27,059,733 passengers served, just missing the record set in 2019.

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.