There are 9 US Post Offices in Dickinson County serving a total of 26,068 residents equating to 2,896 residents per post office. It's estimated that approximately 41,607 packages are handled across the 9 county post offices annually. Dickinson County is a county in the Upper peninsula of the U.S. state of Michigan. As of the 2010 census, the population was 26,168. The county seat is Iron Mountain. Dickinson is Michigan's newest county, formed in 1891 from parts of Marquette, Menominee, and Iron counties. It was named for Donald M. Dickinson, who served as U.S. Postmaster General under President Grover Cleveland. Dickinson County is part of the Iron Mountain, MI\u2013WI Micropolitan Statistical Area."