The Aerial Lift Bridge is an iconic site in Duluth. Unfortunately, we did not see it let a ship through but it is still quite amazing. It is a hugh bridge in terms of structure. There are apparently two primary types of boats one will see pass through. The “Lakers” (90% of the traffic) are ships built specifically to ply the waters of the Great Lakes. They can be 1,000 feet long and carry 70,000 short tons. They usually last 40 – 50 years and are too large to navigate the St. Lawrence Sea Way. “Salties” are smaller and less buoyant in the fresh water so can’t carry such large loads but can pass through the St. Lawrence Sea Way. Their lifespan is shorter due to their time in salt water.