Marshfield is a city in Wood and Marathon counties in the U.S. state of Wisconsin. It is located at the intersection of U.S. Highway 10, Highway 13 and Highway 97. The population was 18,929 at the 2020 census; of this, 18,119 were in Wood County and 810 were in Marathon County. It is a principal city of the Marshfield–Wisconsin Rapids micropolitan statistical area, which includes all of Wood County and had a population of 74,207 in 2020.