Lewisville is a town in Forsyth County, North Carolina, United States. The population was 13,388 at the 2020 census, up from 12,639 in 2010. I…Lewisville is a town in Forsyth County, North Carolina, United States. The population was 13,388 at the 2020 census, up from 12,639 in 2010. It is a Piedmont Triad community. Lewisville incorporated on August 13, 1991.