California Department of Transportation
 

Office of Land Surveys

Scanned USGS Topographic Maps (Digital Raster Graphics or DRGs)

California Teale Albers Projection using the NAD83 datum are now available for free download from the California Spatial Information Library (CaSIL) at http://www.gis.ca.gov

CaSIL has 2 sites for DRG data:

UC Davis, CA, http://casil.ucdavis.edu/casil/gis.ca.gov/drg/

Sacramento, CA, http://casil-mirror1.ceres.ca.gov/casil/gis.ca.gov/drg/

Currently, only the UC Davis site has all the available Albers NAD83 DRG products. The Sacramento site will be mirroring the rest of it eventually. The NAD27 DRGs also remain available at both sites. The NAD83 set has been converted to GeoTIFF format with projection information stored internally - this information is recognized by software such as ArcGIS/ArcMap for on-the-fly projection (as an example, try viewing an Albers NAD83 DRG with a UTM NAD83 DOQ airphoto in GeoTIFF format - they will display together automatically despite the projection differences).

The following DRG sets are available in Albers NAD83:

7.5-minute/24K trimmed
7.5-minute/24K trimmed mosaics

30x60-minute/100K trimmed and untrimmed
30x60-minute/100K trimmed mosaics

1x2-degree/250K trimmed and untrimmed
1x2-degree/250K trimmed mosaics

Some of the NAD83 metadata files are in transition from NAD27 and may indicate the wrong datum.

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