The U.S. Geological Survey (USGS) produces topographic maps at a variety of scales. The most detailed USGS topographic maps for the United States are at 1:24,000 or 1:25,000 scale, covering an area representing 7.5 minutes of latitude by 7.5 minutes of longitude. These maps include natural features, such as mountains, valleys, plains, lakes, rivers, and vegetation. Contours are used to show elevation. The Quad Map Outlines show the extent of each of these maps along with the map name.
For more information on the Quad Map index, visit
http://nationalatlas.gov/mld/idx24kp.html.