There are 31 US Post Offices in Dane County serving a total of 434,020 residents equating to 14,001 residents per post office. It's estimated that approximately 692,744 packages are handled across the 31 county post offices annually. Dane County is a county in the U.S. state of Wisconsin. As of the 2010 census, the population was 488,073, making it the second-most populous county in Wisconsin. The 2015 estimate places the county's population at 523,643. The county seat is Madison, which is also the state capital. Dane County is part of the Madison, Wisconsin, Metropolitan Statistical Area, as well as the Madison-Janesville-Beloit Combined Statistical Area."