Wausau is a city in and the county seat of Marathon County, Wisconsin, United States. The Wisconsin River divides the city into east and wes…Wausau is a city in and the county seat of Marathon County, Wisconsin, United States. The Wisconsin River divides the city into east and west. The city's suburbs include Schofield, Weston, Mosinee, Merrill, Brokaw, Maine, Rib Mountain, Kronenwetter, and Rothschild.