Hager City is an unincorporated census-designated place located in the town of Trenton in Pierce County, Wisconsin, United States, across the Mississippi River from Red Wing, Minnesota. It is located near the intersection of State Highway 35 and U.S. Route 63. Hager City is served by the Ellsworth School District. As of the 2010 census, its population is 338. Hager City has an area of 1.937 square miles; 1.932 square miles of this is land, and 0.005 square miles is water.