Duncanville is a city in southern Dallas County, Texas, in the United States. Duncanville city is part of the Best Southwest area, which includes Duncanville, Cedar Hill, DeSoto, and Lancaster. Duncanville residents incorporated the city on August 2, 1947. The Texas Historical Commission has designated the City of Duncanville as an official Main Street City. Duncanville recognizes the importance of the former Duncanville Air Force Station. Various pieces of the city’s history are preserved at the Duncanville Historical Park, which is located on Wheatland Road in Armstrong Park on land that was once a part of the Duncanville Air Force Station.