Access Illinois GIS data sets and documentation (metadata) for ArcIMS Interactive Map Services, USGS digital topographic maps, aerial photography, orthoimagery, orthophotography, geology, land use, natural resources, and infrastructure. Illinois data sets and map data layers are available for download free of charge. The county has a wealth of map information that it wants to share with the public. Begin your search by entering an address, property identification number(PIN), or intersection. 10 digit PIN Address Intersection.