Fargo is a city in Cass County, North Dakota in the United States. It is the county seat of Cass County, located in the Red River Valley region. The population was 90,599 at the 2000 census (2004 city estimate: 98,084) (2005 Census Bureau estimate: 90,934), which makes it the largest city in North Dakota. Along with West Fargo, North Dakota and Moorhead, Minnesota, it forms the center of the Fargo-Moorhead Metropolitan Area. The metropolitan area has a population of 174,367 and encompasses a lar