Mayville is a city in Dodge County, Wisconsin, United States, located along the Rock River and the Horicon Marsh. The population was 5,196 at t…Mayville is a city in Dodge County, Wisconsin, United States, located along the Rock River and the Horicon Marsh. The population was 5,196 at the 2020 census. Mayville is located at 43°29′49″N 88°32′52″W / 43.49694°N 88.54778°W.