The competition between Duluth and Superior was not idle bickering -- it was a fight over the economic future of the western Great Lakes. The construction of the first locks on the St. Marys River in 1855 had opened navigation between the Great Lakes, and Superior Bay offered a natural sheltered harbor. But Duluth sat on the wrong side of a seven-mile-long sandbar. Ships had to round the entire length of Minnesota Point and pass Superior's docks to reach the open lake. An 1865 breakwater harbor built outside the bay was destroyed by a storm in 1871. The canal through Minnesota Point solved the problem permanently, but at a diplomatic cost: the injunction was lifted only after Duluth agreed to build a dike from Rice's Point to Minnesota Point, isolating the canal from the main flow of the Saint Louis River that fed the bay and formed the border between the two cities.

From the beginning, the canal was defined by piers on either side -- timber cribs placed by the city with some federal funding. Lake Superior's winters proved merciless. Ice and storms battered the wooden structures, requiring substantial repairs every few years. The cycle of damage and rebuilding continued until an 1896 reconstruction project gave the piers their permanent form: concrete set on timber and stone cribbing. The new south pier was completed in 1901, the north pier in 1902. Three lighthouses now mark the canal's passage: the Duluth North Pier Light and the Duluth South Breakwater Outer Light guide ships at the lake entrance, while the Duluth South Breakwater Inner Light serves as a range light paired with the outer one. There are no locks. Ships transit the canal under their own power, though tug service stands ready for foul weather.

Cutting the canal solved the harbor problem but created a new one: Minnesota Point was now an island, severed from the mainland. In 1905, an aerial transfer bridge was constructed to carry passengers and vehicles across the gap in a suspended gondola car. That original structure was converted in 1929 into the Aerial Lift Bridge that stands today, its road deck rising vertically on counterweighted towers to let ships pass beneath. The bridge has become Duluth's most recognizable landmark, its silhouette printed on everything from postcards to brewery labels. At the harbor end of the canal, a Corps of Engineers administration building completed in 1906 anchors the north side. It was enlarged in the 1940s, and in 1973 the Lake Superior Maritime Visitor Center was added, giving tourists a front-row seat to watch thousand-foot ore carriers glide through the narrow passage.

The Duluth-Superior port remains one of the busiest inland ports in North America, handling roughly a thousand vessel transits through the canal each year. Iron ore from the Mesabi Range, grain from the northern plains, coal, limestone, and other bulk commodities move through this narrow cut in the sand. Ocean-going ships, so-called salties, make the journey from the Atlantic through the St. Lawrence Seaway, through the locks at Sault Ste. Marie, across Lake Superior, and into the canal -- a passage that connects the heart of the continent to the world. The breakwaters that define the canal's entrance extend into the lake, their concrete surfaces weathered by more than a century of Superior's notorious storms. From the water, the view approaching the canal is unmistakable: two parallel walls, three lighthouses, and the Aerial Lift Bridge rising against the Duluth hillside.