Lewisville is a city in Denton County, Texas, United States, that barely overlaps with Dallas County, Texas. It is a suburb within the Dallas–Fort Worth Metroplex. The 2000 United States Census placed the city's population at 77,737 and the 2010 Census placed it at 95,290, making it one of the fastest-growing city populations in the United States and the 33rd most populous in Texas. It occupies 36.4 square miles of land and includes 6.07 square miles of Lewisville Lake.