Union County is a county located in the U.S. state of North Carolina. As of the 2020 census, the population was 238,267. Its county seat is Monroe. Union County is included in the Charlotte-Concord-Gastonia, NC-SC Metropolitan Statistical Area.

Monroe is a city in and the county seat of Union County, North Carolina, United States. The population increased from 32,797 in 2010 to 34,551 in 2020. It is within the rapidly growing Charlotte metropolitan area. Monroe has a council-manager form of government.