There are 12 US Post Offices in Marinette County serving a total of 43,237 residents equating to 3,603 residents per post office. It's estimated that approximately 69,011 packages are handled across the 12 county post offices annually. Marinette County is a county located in the U.S. state of Wisconsin. As of the 2010 census, the population was 41,749. Its county seat is Marinette, which now includes the former independent village of Menekaunee as a neighborhood. Marinette County is part of the Marinette, WI\u2013MI Micropolitan Statistical Area."