Postville is a village in Allamakee and Clayton counties in the U.S. state of Iowa. It lies near the junction of four counties and at the intersection of U.S. Routes 18 and 52 and Iowa Highway 51, with airport facilities in the neighboring communities of Waukon, Decorah, Monona and Prairie du Chien. The population was 2,503 at the time of the 2020 census, up from 2,273 in 2000. The village is in Allamakee County's southwestern corner and the Clayton County's northwestern corner in a quad county, or four-corner region, where four counties intersect. Winneshiek County is just to the west and Fayette County just to the southwest of Postville.