Story County is a county in the U.S. state of Iowa. As of the 2020 census, the population was 98,537, making it the ninth-most populous county in Iowa. The county seat is Nevada; the largest city is Ames. The geographical center of Iowa lies in Story County, 5 miles northeast of Ames. Story County comprises the Ames, IA Metropolitan Statistical Area, which is included in the Des Moines-Ames-West Des Moines, IA Combined Statistical Area. The county is home to Iowa State University in Ames.