Pennsylvania's anthracite lay buried in isolated, rugged mountain valleys north and west of the turbulent Lehigh River, and although it promised profits in downstream markets, low-cost transportation was a major obstacle. By the beginning of the 19th century, businessmen worked toward a solution in the Lehigh Navigation, a civil engineering feat that overcame an almost 1,000-foot elevation drop between White Haven and Easton through a creative system of dams, hand-dug channels, and calm river stretches. It eventually became known as the largest-capacity and longest-running towpath canal in America, and the section between Mauch Chunk, today's Jim Thorpe, and Easton still has towpath trails and watered sections. Though it remained successful longer than most because of its location and the industries it spawned, the canal finally closed as costly floods, railroad systems, evolving highway networks, and declining coal sales took their toll. The last boat moved along the canal on the evening before the flood of 1942, ending an era and a way of life, and boat captains had long warned locktenders of their approach with horns, often conch shells.