Poweshiek County is a county in the southeastern part of the U.S. state of Iowa. As of the 2020 census, the population was 18,662. The county seat is Montezuma. The county is named for the chief of the Fox tribe who signed the treaty ending the Black Hawk War. It lies along Interstate 80 between Des Moines and Iowa City. Poweshiek County's largest city is Grinnell.

Interstate 80 (I-80) is a transcontinental Interstate Highway in the United States, stretching from San Francisco, California, to Teaneck, New Jersey. In Iowa, the highway travels west to east through the center of the state. It enters the state at the Missouri River in Council Bluffs and heads east through the southern Iowa drift plain. In the Des Moines metropolitan area, I-80 meets up with I-35 and the two routes bypass Des Moines together. On the northern side of Des Moines, the Interstates split and I-80 continues east. In eastern Iowa, it provides access to the University of Iowa in Iowa City. Northwest of the Quad Cities in Walcott is Iowa 80, the world's largest truck stop. I-80 passes along the northern edge of Davenport and Bettendorf and leaves Iowa via the Fred Schwengel Memorial Bridge over the Mississippi River into Illinois.