Baltimore-Washington International Thurgood Marshall Airport (IATA: BWI, ICAO: KBWI) serves the Baltimore-Washington Metropolitan Area in the United States. It is commonly referred to as BWI or BWI Airport, after its IATA Airport Code. The airport is located in Anne Arundel County, Maryland and is about 10 miles (16 km) south of Baltimore and 30 miles (48 km) northeast of Washington, D.C.

A record 21.04 million passengers passed through BWI in 2007, a 1.7% increase over 2006, making it the United States' 24th busiest airport. In 2006, traffic grew by 4.8%, to 20.7 million people.

BWI Rail Station opened in 1980, providing a rail connection to passengers on the busy Northeast Corridor. BWI became first airport in the U.S. to be served by a dedicated intercity rail station. In particular, the station provided relatively easy transit access to Washington, D.C., something Dulles International Airport lacks. In the late 1990s, a new international terminal (Concourse E) was added, though Dulles continues to hold the lion's share of the region's international flights. British Airways and Icelandair have had a presence at BWI for many years.