1. Post route map of the state of Minnesota : showing post offices with the intermediate distances on mail routes in operation on the 1st of December 1928 Maps University Of Minnesota Public content 1928. United States. Post Office Department. Includes list of counties.; Insets: Duluth and vicinity. Scale [ca.1:200,000] -- [Cook County, Minnesota] -- St. Paul, Minneapolis and vicinity. Sc... Post Office Dept (Washington, D.C.?).