Southwest Washington Regional Airport (IATA: KLS, ICAO: KKLS, FAA LID: KLS) is a city-owned public-use airport located two nautical miles (3.7 km) southeast of the central business district of Kelso, in Cowlitz County, Washington, United States.

Kelso-Longview Airport opened in May 1941 on 109 acres (0.44 km2) of a nearby dairy farm,[3] as a training field for amateur pilots, and has since become a regional transportation center for southwest Washington.

[3] Southwest Washington Regional Airport covers an area of 110 acres (45 ha) at an elevation of 20 feet (6 m) above mean sea level.

[1] It is separated for takeoffs and landings (the airport, faced with growing air traffic, segmented its runway in 1980).

[3] For the 12-month period ending March 30, 2008, the airport had 40,860 aircraft operations, an average of 111 per day: 94% general aviation, 4% air taxi and 2% military.