Plymouth is a city in Sheboygan County, Wisconsin, United States, along the Mullet River. The population was 8,932 at the 2020 census. It is i…Plymouth is a city in Sheboygan County, Wisconsin, United States, along the Mullet River. The population was 8,932 at the 2020 census. It is included in the Sheboygan, Wisconsin metropolitan area. The city is located in the Town of Plymouth, but is politically independent. Plymouth was known as "Hub City" for its former role as a center of wooden wheelwrighting. It is now known as "The Cheese Capitol of the World" as it produces 40% of all the cheese consumed in the United States. Mayor Don Pohlman was last re-elected in April 2018.