Gastonia is the most populous city in and the county seat of Gaston County, North Carolina, United States. It is the second-largest satellit…Gastonia is the most populous city in and the county seat of Gaston County, North Carolina, United States. It is the second-largest satellite city of the Charlotte area, behind Concord. The population was 80,411 in the 2020 census, up from 71,741 in 2010. Gastonia is the 13th-most populous city in North Carolina. It is part of the Charlotte-Concord-Gastonia, NC-SC Metropolitan Statistical Area, which is part of the Charlotte-Concord, NC-SC Combined Statistical Area.