The majority of topographic maps in our collection are from the USGS 7.5 Minute series. These maps were produced at a scale of 1:24,000 and cover an area 7.5' x 7.5' (one-eighth of a degree square). One inch represents 2,000 feet. These maps display elevation, major landmarks, buildings, vegetation, and other large man-made structures. (Google Earth can provide more detailed images.) Paper copies are no longer produced; the government now produces freely downloadable US Topo maps which are updated on a three-year cycle. (Additional information below.)
The maps are arranged by state and then alphabetical by quadrangle name.
The quadrangles (quads) are arranged on a grid, and if you know your area you can find the quad name using the paper indexes in the first drawer of each state 1:24,000 section. Here is an online example of the Illinois topographic index map.
The Geographic Names Information System (GNIS) can also be used to identify the name of the appropriate topographic map.
Using the Search Topographic Map Cells option, select the "Search Topographic Map/Digital Product Cells" option on the far right ... then enter the place name of interest in the Feature Name field and select the state with the pull-down menu. Look for the Cell Name (name of the quad map) that has a Cell Size of "7.5 X 7.5 Minute". See the video of searching for a place name.
FREE ONLINE COLLECTION
The USGS now provides regularly updated US Topo free online topoographic maps. These maps are not as detailed as the older paper maps, but new layers are being added on a periodic basis. (HINT: For the exact name of the corresponding older paper map, search for a specific location, and then click the red marker for the name of the earlier paper quadrangle map.)
Historical topographic maps are also available online.
Historical Note: Recent USGS digital US Topo 1:24,000 topo maps based on the National Map omit several important geographic details that were featured in the original USGS topographic map series (1945-1992). Examples of omitted details and features include power transmission lines, telephone lines, railroads, recreational trails, pipelines, survey marks, and buildings. For many of these feature classes, the USGS is working with other agencies to develop data or adapt existing data on missing details that will be included in The National Map and to US Topo. In other areas USGS digital map revisions may omit geographic features such as ruins, mine locations, springs, wells, and even trails in an effort to protect natural resources and the public at large, or because such features are not present in any public domain database. See the recent update summary.
NOTE: The USGS also produces intermediate-scale topographic at scales of 1:100,000 and 1:250,000 that cover 30' x 60' (one half of a degree by a degree) and 1° x 2° (one by two degrees), which are located in separate cabinets.