Sanborn Maps, 1867-1970: Illinois This link opens in a new windowThis unique collection of maps was originally created to help fire insurance companies determine the risks associated with insuring properties. Because the maps were created over a century, they are useful in charting the development of cities and towns over many years. Encompasses most towns and cities in Illinois and is valuable to genealogists, local historians, city planners, environmentalists, geographers and architects. Extensive information on building use is given including names of owners of factories and details on what was manufactured in them.