Data files are offered as original USGS DRG .tif files. One uncompressed file is roughly 4 megabytes in size.

A statewide collection of 1:24,000 scale quadrangle data requires about 2.6 Gigabytes of storage space. We do not plan to distribute uncompressed data files by any other means (cd-rom, zip drives, portable drives, ftp download, etc).

USGS DRG data for Illinois are available free-of-charge via:

an interactive map,

a list of 1:24,000 scale quadrangles (1,071 files) for data download,

a list of 1:100,000 scale quadrangles (51 files) for data download, and

a list of 1:250,000 scale quadrangles (17 files) for data download. 

    Uncompressed .zip file bundles contain:

README.txt - a text copy of this file listing,

<filename>.tif - TIFF image,

<filename>.tfw - Companion Georeferencing file,

<filename>.fgd - The original USGS metadata, and

<filename>.updated.met - IDNR modified metadata. 

Metadata:

Sample original USGS 1:24,000 quadrangle metadata for UTM data by zone.

Sample original USGS 1:100,000 quadrangle metadata for UTM data by zone.

Sample original USGS 1:250,000 quadrangle metadata for UTM data by zone. 

Note: the USGS changed the name of the 1:24,000 Eaton Quadrangle to Porterville. 

File index:

The USGS Topographic Map Index (5.2 MB) can assist you in locating a 1:24,000 scale quadrangle. 

1:100,000 and 1:250,000 scale quadrangles are in tables that approximate the shape of Illinois.