The original plats and field notes for an area can be useful to understand how an area has changed in the last 150 or more years. These are available on microfilm at the Daley Library and online through the General Land Office (GLO).
For more information, see M.D. Hutchinson (1988) "A Guide to Using the Public Land Survey Field Notes in Illinois." Natural Areas Journal 8: 245-255.
SimplyMap allows UIC faculty, staff, and students to create maps using a wide range of demographic and marketing data and information. Mapping can be done to small units of geography such as census tracts and ZIP codes.
USGS maps include:
7.5' maps of all states with state index maps in the first map case drawer for each state
15' maps of all states with state index maps in the first drawer for each state
BLM Surface and Mineral maps with a national index map in the first drawer of the Surface maps