Provide a Raster Mosaic of the Historic Maps Produced by USGS, The 7.5 minute topographic maps were produced at scale of 1:24,000. The date ranges for the maps used for this mosaic are 1951 - 2002. Maps were downloaded from the USGS Topo View site in PDF format and then exported out to TIFF and georeferenced.

The best known USGS maps are those of the 7.5-minute, 1:24,000-scale quadrangle series. A scale of 1:25,000 is used for maps based on metric units (1 centimeter = 0.25 kilometer). The area portrayed on each sheet ranges from 64 square miles at latitude 30 degrees north to 49 square miles at latitude 49 degrees north.

A scale of 1:24,000 allows considerable detail to be shown in the quadrangle areas. It takes about 57,000 maps to cover the conterminous 48 States, Hawaii, and territories.

The sheet size is about 22 x 27 inches north of latitude 31 degrees and 23 x 27 inches south of that latitude.