Maps (both printed and manuscript), blueprints, plans, sketches, and bound plats, showing various properties of the Illinois Central Railroad. Most of the maps are from the Department of the Chief Engineer, and include land surveys, tracks, passenger houses, freight houses, stations, proposed and actual construction, right of way, and other details of buildings, land, and equipment. Two series of maps, originally found in the 1951 Mohr guide as Appendix C (pp.179-181, nos. 1-33) and as IC +3.81 (p. 45 and pp. 182-183, nos. I-XXVI), are incorporated into this record group. The record group also houses a small number of non-geographic drawings.

Occasionally, if maps are of general scholarly interest and do not apply specifically to the Illinois Central, they have been removed from the IC collection and recataloged into the Newberry Library's main map collection. They are still identified as Illinois Central maps, but they are given a Library of Congress call number and are interfiled with the other Newberry maps.