USGS 24k Digital Raster Graphics Topographic Map

This map is locally hosted at boydsmaps.com

Data Sources

Description

The 24k (7.5 minute) topographic maps were first digitized using the USGS Digital Raster Graphics format during the period 1995 to 1998. The original paper maps were scanned at a resolution of 250 dots per inch (8 feet per pixel). Although the resolution is high enough, they constrained the palette to only 12 colors which resulted in artifacts and difficult-to-read text.

According to a 2001 USGS report, national DRG coverage was completed by 1998 but they continued updating about 1000 maps to new versions each year. It is not clear when production of the DRG topo's ended. They were widely used through Microsoft's Terraserver website starting in the late 1990's. The USGS offered the DRG's for download through their seamless server but discontinued them many years ago.

In spite of their shortcomings, we feel the DRG Topo's have enough historical significance to host them. It was a bit of a challenge to find DRG sources in 2025 however. The core of the map is actually the original terraserver topo, downloaded with USAPhotoMaps software around 2004. Cornell University has archives of the New York 24k DRG's and Pennsylvania Spatial Data Access (PASDA) was a good source for PA, NY, DE and MD. We were unable to find 24k DRG's for Connecticut or Rhode Island however and used maps from the USGS Historic Topographic Map Collection; you will notice the quality difference in these maps. The Massachusetts 24k maps are mosaics created by MassGIS and not original DRG's.

The 24k topos are shown at zoom levels 14, 15 and 16. 100k DRG's are displayed at zoom level 13 and 250k DRG's are shown at levels 6 through 12. Again, the core of these maps came from the author's archives, supplemented primarily from the PASDA collection.

This map also provides period-correct topos for the boydsmaps terraserver translator which can open old links to the now-discontinued website.

Please see our 24k Legacy Topo for a higher quality version of these maps with a greater coverage area.

You can compare the two versions with our MapSync App.

Resources

See the following document for information about the symbols that are used on USGS topographic maps:

A document explaining topographic map scales is available here:

USGS digital raster graphics report from 2001:

Credits

United States Geological Survey, USGS Historic Topographic Map Collection, Pennsylvania Spatial Data Access (PASDA), Massachusetts Bureau of Geographic Information Systems, Cornell University Geospatial Information Repository

Distribution Liability

The U.S. Geological Survey makes no expressed or implied warranty regarding the accuracy or utility of the data for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein.

The digital version of these historical maps were georeferenced with a methodology that preserves, but does not exceed, the accuracy of the original map. The historical map product was compiled to meet National Map Accuracy Standards (NMAS) of the era when the map was originally published. Users should be aware that temporal changes may have occurred since this map was originally produced and that some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

Map software is provided "as is.", without any express or implied warranty. In no event will boydsmaps.com be held liable for any damages arising from the use of this software. The user assumes all risks associated with the use of this software. boydsmaps.com will not be held responsible for any inaccuracies and no responsibility is assumed for damages or other liabilities due to errors, installation, accuracy, availability, use or misuse of the data presented.