St. Louis County is a county located in the U.S. state of Minnesota. As of 2000, the population was 200,528. Its county seat is Duluth. It is the largest county in Minnesota, and the second largest in the United States east of the Mississippi River; Aroostook County, Maine, is the largest. Major industries include pulpwood production and tourism. At one time, taconite mining was a major part of the economy. Parts of the Bois Forte and Fond du Lac Indian reservations are in the county.