Manhattan is a city locate in the northeastern part of the U.S. state of Kansas at the junction of the Kansas River and Big Blue River. As of the July 2006 census estimate, its population was 50,737, making it the eighth-largest city in Kansas. Manhattan is the county seat of Riley County. A small part of the town extends into Pottawatomie County. It is the principal town within the Manhattan, Kansas Micropolitan Statistical Area.