Prehistoric cultural affiliation(s) include Middle Woodland and Late Woodland dating back to 499 BC.
Several famous people are associated with these Hardin County historic places including Eugene S. Ellsworth and Eva Harrington Simplot.
Some of the country's most noteable architects helped create the Hardin County places including Iowa State Highway Commission, Weldon Brothers, Illinois Central Railroad, Patton & Miller, Wetherell & Gage, J.H. Schott, Coomer & Small Construction Co., Des Moines Bridge and Iron Works, Weldon Brothers Constuction Co. and Marsh Eng. Co.. Prominent architectural styles found in Hardin Country are Classical Revival, Late 19th And 20th Century Revivals and Renaissance.