The older Primary Base Series maps are derived from the U.S. Geological Survey topographic quadrangles and modified by the USDA Forest Service. They are highly detailed maps showing lands managed by the Forest Service in green and serve as the base for all other Forest maps. The newer Single Edition Quads use new, but identical symbology regarless of which Agency compiles them and land inside the National Forest boundary not managed by the Forest Serivce is gray. Depending on the size Forest, between 30 -175 maps are needed for complete coverage. Topography is shown with a contour interval of 10 or 20 feet.
Maps are also available from other sources.
The U.S. Geological Survey has topographic quadrangle maps covering all areas of the country.