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 AND DEWEY Readmore Books, the Library Cat . The fair averages over 300,000 visitors per year. Spencer was ranked 10th best place to live in the United States by Relocate-America. com's "America's Top 100 Places to Live for 2007."