Hancock is a city in Pottawattamie County, Iowa, United States, along the West Nishnabotna River. The population was 200 at the time of the 2…Hancock is a city in Pottawattamie County, Iowa, United States, along the West Nishnabotna River. The population was 200 at the time of the 2020 census. Hancock got its start in the year 1880, following construction of the Rock Island Railroad through the territory. It was named for its founder, F. H. Hancock.