Printmaker and illustrator Joseph Pennell illustrated 100 books throughout his career and was influenced in style by his friend James McNeill Whistler. Pennell traveled the world, producing etchings, pen-and-ink drawings, and lithographs of cathedrals, plazas, street scenes, and palaces. He also made panoramic views of major construction and engineering projects, such as the Panama Canal and the locks at Niagara Falls. During World War I, he created a number of important poster designs for the Division of Pictorial Publicity of the Committee on Public Information, which was organized to build support for the war when the United States entered it in 1917. The Gatun Locks are located in the Panama Canal and raise ships up to 85 feet, to the main elevation of the Panama Canal and down again. The design and manufacture of the lock gates was one of the Canal’s greatest engineering challenges and triumphs. The construction process took four years and used a record setting amount of concrete.