- Cass County, Minnesota has 2,021.5 square miles of land area and is the 6th largest county in Minnesota by total area. Cass County, Minnesota is bordered by Aitkin County, Minnesota, Hubbard County, Minnesota, Beltrami County, Minnesota, Morrison County, Minnesota, Wadena County, Minnesota, Itasca County, Minnesota, Todd County, Minnesota, and Crow Wing County, Minnesota.