Duluth, Minnesota Lakes Waterway and the Saint Lawrence Seaway. Duluth forms a metropolitan area with neighboring Superior, Wisconsin, called the Twin Ports. The cities share the Duluth–Superior harbor and together are the Great Lakes' largest port, transporting coal, iron ore (taconite), and grain. A tourist destination for the Midwest, Duluth features the United States' only all-freshwater aquarium, the Great Lakes Aquarium; the Aerial Lift Bridge, which spans the Duluth Ship Canal into the Duluth–Superior Harbor; and Minnesota Point (known locally as Park Point), the world's longest freshwater baymouth bar, spanning . The city is also the starting point for vehicle trips along
Duluth, Minnesota took first place. The Minnesota state gem, the Lake Superior agate, can be found on the shores of Lake Superior or the streams that run into it, and in gravel pits and road cuts. Duluth's Park Point is an excellent area for hunting. Shorelines and beaches are replenished each year because winter ice and storms push new material up on the shores. Books are available in Duluth to help amateur rock hounds learn more about agates, and how to locate them. Since 1977, Duluth has played host to Grandma's Marathon, held annually in June. Named after its original sponsor, Grandma's