The First Atlas of Union County Illinois Territory is a historical reference for the lands encompassing Union County in the Illinois Territory from 1809 to 1818. At the time Union County included land that now makes up Alexander and a part of Pulaski counties in southern Illinois. The reference book includes illustrated township plats that document the names of settlers, squatters, and speculators who occupied them during the time. It also includes the platted location of paths, trails, and roads, and the ferries that operated on the Mississippi, Ohio, and Cache rivers. Stories are included about the settlement of southern Illinois, an area that came to be known as "Egypt", and the spirit of the people who were once a part of its citizenry. The history is grounded in the enlightenment period that followed the Revolutionary War and highlights its impact on the establishment of a newly formed country.