The area is diverse, with the northern part being woods, mid section being rich in iron deposits, and the southern and eastern sections heavy in tourism.
The seat and largest city is Duluth. It is named for the St. Louis River, which is named for a river an early French explorer was to cross.
The current county was formed in 1857 out of Doty (later Newton), Superior, Lake and Carlton Counties.
The county borders Koochiching, Itasca, Aitkin, Carlton and Lake Counties in Minnesota, Douglas County in Wisconsin, Rainey River District in Ontario (Canada) and Lake Superior.
Main Highways include I-35, I-535, US-53, US-2, US-169, MN-1, MN-23, MN-22, MN-61, MN-210, St. Louis County 4 and 13.
The area contains many rural bridges. Currently I have only worked in the southern part of the county.