St. Croix State Park is a state park in Pine County, Minnesota, USA. The park follows the shore of the St. Croix River for 21 miles (34 km) and contains the last 7 miles (11 km) of the Kettle River. At 33,895 acres (13,717 ha) it is the largest Minnesota state park. It was developed as a Recreational Demonstration Area in the 1930s, and is one of the finest surviving properties of this type in the nation. 164 structures built by the Civilian Conservation Corps and the Works Progress Administration survive, the largest collection of New Deal projects in Minnesota. As a historic district they were listed on the National Register of Historic Places and proclaimed a National Historic Landmark in 1997.