Radcliffe is a city in Hardin County, Iowa, United States. The population was 555 at the time of the 2020 census. Radcliffe was laid out in 188…Radcliffe is a city in Hardin County, Iowa, United States. The population was 555 at the time of the 2020 census. Radcliffe was laid out in 1880 when the railroad was extended to that point. It was named after the novel The Heir of Redclyffe by Charlotte Mary Yonge.