Detroit Metropolitan Wayne County Airport (IATA: DTW, ICAO: KDTW, FAA LID: DTW) is the primary international airport serving Detroit and its surrounding metropolitan area, in the U.S. state of Michigan. It is located in Romulus, a Detroit suburb. It is by far Michigan's busiest airport, with 10 times as many enplanements and deplanements as the next busiest, Gerald R. Ford International Airport in Grand Rapids, and more than all other airports in the state combined.

The Federal Aviation Administration (FAA) National Plan of Integrated Airport Systems for 2017–2021 categorized it as a large hub primary commercial service facility. The airport covers 4,850 acres (1,960 ha) of land.

The airport is the second-largest hub for Delta Air Lines and also a base for Spirit Airlines. The airport has service to 30 international destinations and to 39 states across the United States. Operated by the Wayne County Airport Authority, the airport has six runways, two terminals, and 129 in-service gates. Detroit Metropolitan Airport has maintenance facilities capable of servicing and repairing aircraft as large as the Boeing 747-400.

Metro Airport serves the metropolitan Detroit area; the Toledo, Ohio, area about 40 miles (64 km) south; the Ann Arbor area to the west; Windsor, Ontario; and Southwestern Ontario in Canada. The airport serves over 140 destinations and was named the best large U.S. airport in customer satisfaction by J.D. Power & Associates in 2010, 2019, and 2022.

Wayne County began to plan an airport in the western townships of the county as early as 1927. The following year, the county board of commissioners issued a $2 million bond to fund the purchase of one square mile (2.6 km²) of land at the corner of Middlebelt and Wick roads, the northeastern boundary of today's airport. Construction was completed in 1929, and the first landing was on February 22, 1930; Wayne County Airport was dedicated on September 4, 1930. That year, Thompson Aeronautical Corporation, a forerunner of American Airlines, began service from the airport. From 1931 until 1945, the airport hosted Michigan Air National Guard operations gained by the United States Army Air Forces. It was named Romulus Field during the war; it was then all east of Merriman Road and north of Goddard Road. The intersection of the two runways is still visible at 42°13′58″N 83°20′08″W / 42.23266°N 83.33564°W / 42.23266; -83.33564.

Wayne County expanded the airport to become Detroit's primary airport. It renamed it Detroit-Wayne Major Airport in 1947, and in the next three years expanded threefold as three more runways were built. In 1949 the airport added runways 3L/21R and 9L/27R, followed by runway 4R/22L in 1950. In 1946-47 most airline traffic moved from the cramped Detroit City Airport (now Coleman A. Young International Airport) northeast of downtown Detroit to Willow Run Airport over 20 miles (32 km) west of the city, and 10 miles (16 km) west of Wayne County Airport.

Pan Am (1954) and BOAC (1956) were the first passenger airlines at Detroit-Wayne Major. In the April 1957 Official Airline Guide they were the only passenger airlines: three Pan Am DC-7Cs each week FRA–LHR–SNN–DTW–ORD and back, and one BOAC DC-7C each week LHR–PIK–YUL–DTW–ORD and back (skipping YUL on the return flight).

Aerial photographs of DTW from 1949 and 1956 show the airport's expansion. In 1958 the Civil Aviation Administration—now the Federal Aviation Administration (FAA)—announced the inclusion of Detroit-Wayne in the first group of American airports to receive new long-range radar equipment, enabling the airport to become the first inland airport in the United States certified for jet airliners. Also, in 1958, airport management completed the Leroy C. Smith (South) Terminal and gave the airport its present name.