Rockwell City is a city and the county seat of Calhoun County, Iowa, United States. The population was 2,240 in 2020. Rockwell City was …Rockwell City is a city and the county seat of Calhoun County, Iowa, United States. The population was 2,240 in 2020. Rockwell City was platted in 1876. It is named for its founders, John M. Rockwell, and his wife Charlotte M. Rockwell.