St. Croix County is a county in the U.S. state of Wisconsin. As of the 2020 census, the population was 93,536. Its county seat is Hudson. The county was created in 1840 and organized in 1849. St. Croix County is part of the Minneapolis-St. Paul-Bloomington, MN-WI Metropolitan Statistical Area. Between 2000 and 2010, it was the fastest-growing county in Wisconsin.

Hudson is a city and county seat of St. Croix County, Wisconsin, United States. As of the 2020 United States census, its population was 14,755. It is part of the Minneapolis–St. Paul Metropolitan Statistical Area (MSA). The village of North Hudson is directly north of Hudson.