Blairstown is a city in Benton County, Iowa, United States. The population was 713 at the 2020 census. It is part of the Cedar Rapids Metropolit…Blairstown is a city in Benton County, Iowa, United States. The population was 713 at the 2020 census. It is part of the Cedar Rapids Metropolitan Statistical Area. Blairstown was platted in 1862. It was surveyed in the spring of 1862 by George F. Kirby who also surveyed Belle Plaine. It was named for its proprietor and railroad magnate, John Insley Blair who also founded Belle Plaine.