Waxhaw is an incorporated town in Union County, North Carolina, United States. The population was 20,534 according to the 2020 Census. Th…Waxhaw is an incorporated town in Union County, North Carolina, United States. The population was 20,534 according to the 2020 Census. The population grew 108.28% from 2010. The name is derived from the indigenous people who lived in the area, who were known as the Waxhaw people.