Historical Topographic Maps

Current US Topo maps, and maps of the Historical Topographic Map Collection (HTMC). are published as PDF documents that can be downloaded free of ch
The following table summarizes the map series included in the Historical Topographic Map Collection (HTMC).
In 2015 the National Geoglogic Map Database project mass-converted all GeoPDF HTMC maps to GeoTIFF and several other image formats.
Yes, these are different maps, though the differences are often relatively minor. For a particular cell and scale, most maps have only one original base compilation, but most have later revisions and reprints.
There is no single document that describes all symbols used on all USGS topographic maps.
About 179,000 map sheets have been scanned and published, but we estimate that 10,000 to 20,000 more maps exist. Several thousand have been scanned and are being processed to products as time permits.
The goals of the Historical Topographic Map Collection (HTMC) project are to find, catalog, and georeference all USGS topographic quadrangle maps. The overall purpose is to preserve the map archive for scientists, historians, and the public.
Metadata is defined by the Federal Geographic Data Committee as "the background information which describes the content, quality, condition, and other appropriate characteristics of the data.
The USGS completed the primary topographic map series of the conterminous United States at 1:24,000 in 1992. Revisions were made until 2006. Alaska, Hawaii, Puerto Rico, and Trust Territories were completed earlier and were done at other scales.