Duncanville is a city in Dallas County, Texas (USA). Duncanville's population was 36,081 at the 2000 census, and estimated at 42,500 in 2008. Duncanville is a suburb of Dallas and is part of the Best Southwest area, which includes Duncanville, Cedar Hill, DeSoto, and Lancaster.
Duncanville is located at 32°38′47″N 96°54′41″W / 32.64639°N 96.91139°W / 32.64639; -96.91139 (32.646333, -96.911309).
According to the United States Census Bureau, the city has a total area of 11.3 square miles (29.2 km²), all of it land.