There are 10 US Post Offices in Oconto County serving a total of 31,113 residents equating to 3,111 residents per post office. It's estimated that approximately 49,660 packages are handled across the 10 county post offices annually. Oconto County is a county in the U.S. state of Wisconsin. As of the 2010 census, the population was 37,660. Its county seat is Oconto. The county was established in 1851. Oconto County is part of the Green Bay, WI Metropolitan Statistical Area as well as the Green Bay-Shawano, WI Combined Statistical Area."