It lies in the statistical Twin Cities Metropolitan area, being only 13 miles from the capitol of Minnesota, Saint Paul.
The seat and largest city is Hudson. It is named for the St. Croix River, which forms a large part of the Minnesota-Wisconsin border.
It borders Polk, Barron, Dunn and Pierce Counties in Wisconsin, and Washington County in Minnesota.
Main highways include I-94, US-12, US-63, WI-29, WI-35, WI-65 and WI-64.