There are 17 US Post Offices in Linn County serving a total of 154,861 residents equating to 9,109 residents per post office. It's estimated that approximately 247,175 packages are handled across the 17 county post offices annually. Linn County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 211,226, making it the second-most populous county in Iowa. The county seat is Cedar Rapids. Linn county is named in honor of Senator Lewis F. Linn of Missouri. Linn County is included in the Cedar Rapids, IA Metropolitan Statistical Area."