There are 9 US Post Offices in Dunn County serving a total of 41,268 residents equating to 4,585 residents per post office. It's estimated that approximately 65,868 packages are handled across the 9 county post offices annually. Dunn County is a county in the U.S. state of Wisconsin. As of the 2010 census, the population was 43,857. Its county seat is Menomonie. Dunn County comprises the Menomonie, WI Micropolitan Statistical Area and is included in the Eau Claire-Menomonie, WI Combined Statistical Area."