Lake Elmo Airport (FAA LID: 21D) is a public airport located just outside the city of Lake Elmo in Washington County, Minnesota, United States, about 12 miles east of the central business district of St. Paul. Although most airports in the United States use the same three-letter location identifier for the FAA and International Air Transport Association (IATA), this airport is assigned 21D by the FAA but has no designation from the IATA or ICAO. It is also home to a Civil Air Patrol squadron.