Historical Topographic Maps – Preserving the Past
In 2009, USGS began the release of a new generation of topographic maps (US Topo) in electronic form, and is now complementing them with the release of high-resolution scans of more than 178,000 historical topographic maps of the United States. The topographic map remains an indispensable tool for everyday use in government, science, industry, land-use and management planning, history, and recreation.
As physical and cultural features change over time, maps are updated and revised, and new editions printed. Although out of date, historical maps are often useful to scientists, historians, environmentalists, genealogists and others researching a particular geographic location or area. A series of maps of the same area published over a period of time can show how an area looked before development and provide a detailed view of changes over time.
Because historical maps are stored in a limited number of collections and are not readily available, the USGS National Geospatial Program (NGP) has begun to convert these historical printed topographic quadrangles to an electronic format. This serves the dual purpose of creating a master catalog and digital archive copies of the irreplaceable collection of topographic maps in the USGS Reston Map Library as well as making the maps available for viewing and downloading from the USGS Store and from The National Map Downloader.
Goals for the Historical Topographic Map Collection
The goal of the Historical Topographic Map Collection is to scan all scales and all editions of the more than 178,000 topographic maps published by the USGS since the inception of the topographic mapping program in 1884. The NGP is accurately cataloging and creating metadata to accompany high-resolution, georeferenced digital files representing the legacy lithographic maps. These maps are either no longer available for distribution in print or are being replaced by the new generation of US Topo maps; however, they hold the potential to become chronological layers of The National Map. The potential for research that documents change over time is becoming increasingly recognized by the geospatial community, and this project is providing the previously published lithographic USGS maps in digital form.
Georeferencing of the map files—that is, tying them to a known earth coordinate system—enables importing into Geographic Information Systems so the maps can be overlain with other geospatial data. The potential for research to analyze land-use change over time is becoming increasingly recognized by the geospatial community, and this project supports that work by providing the published USGS topographic maps in georeferenced digital formats. Currently, these maps are available in a compressed GeoPDF format. In the future, they will be delivered in other formats, such as GeoTIFF images with embedded metadata.