Duluth is a port city in the U.S. state of Minnesota and is the county seat of Saint Louis County. The fourth largest city in Minnesota, Duluth had a total population of 86,265 in the 2010 census. Duluth is also the second largest city that is located on Lake Superior after Thunder Bay, Ontario, and has the largest metropolitan area on Lake Superior. The Duluth MSA had a population of 279,771 in 2010. Situated at the westernmost point of the Great Lakes on the north shore of Lake Superior, Duluth is accessible to ocean-going vessels from the Atlantic Ocean 2,300 miles (3,700 km) away via the Great Lakes and Saint Lawrence Seaway.