 Proctor Knott is sometimes credited with characterizing Duluth as the "zenith city of the unsalted seas," but the honor for that coinage belongs to journalist Thomas Preston Foster, speaking at a Fourth of July picnic in 1868.During the 20th century, the Port of Duluth was for a time the busiest port in the United States, surpassing even New York City in gross tonnage.Lake freighters carried iron ore through the Great Lakes to processing plants in Illinois and Ohio.