Duncanville is located in Dallas County, Texas. Duncanville’s population was 38,524 at the 2010 census. Duncanville is a suburb of Dallas and is part of the Best Southwest area, which includes Duncanville, Cedar Hill, DeSoto, and Lancaster.

According to the United States Census Bureau, the city has a total area of 11.3 square miles, all of it land.

The median income for a household in the city was $51,654, and the median income for a family was $57,064. Males had a median income of $39,199 versus $30,145 for females. The per capita income for the city was $22,924. The Average Household Income for the city in 2008 is $82,500. About 3.9% of families and 6.1% of the population were below the poverty line, including 8.2% of those under age 18 and 3.6% of those age 65 or over.