This undated postcard, published by Zenith Interstate News Company, shows a Great Lakes packet freighter passing through the Duluth Shipping Canal under the Aerial Lift Bridge.

The caption on the back reads:

The famous Lift Bridge at the entrance to the Duluth-Superior Harbor is the largest of its kind in the world. The 900 ton span, raised by electrical energy stored in batteries, rises 120 feet in 50 seconds each time a boat enters the harbor. The U.S. Government records show that since 1895 the stupendous total of 1,317,092,019 tons of merchandise, in receipts and shipments, have passed thru this harbor.