Spencer is a city in Clay County, Iowa, United States, at the confluence of the Little Sioux and Ocheyedan Rivers. The population was 11,317 at the 2000 census. It is the county seat of Clay County. Spencer is famous as the home of the Clay County Fair, held annually in September. The fair averages 315,000 visitors per year. Spencer apartments for rent comparison page shows most up to date rent information on Spencer apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.