United States. Geological Survey. U.S.G.S. Alternate title: PA. Smicksburg. Polyconic projection. Relief shown by 20 feet contour interval and spot heights. Surveyed in 1906-1907. Surveyed in cooperation with the State of Pennsylvania. Partial revision in 1938 by D. H. Watson and H. R. Kilmer. Verso: The topographic maps of the United States.