Greene County was established by the laws of Illinois. In 1821, during a period of rapid Euro-American settlement of the Illinois River valley after the War of 1812, the newly organized (1818) state carved a new county out of a territorial super-county, Madison County. The earliest settlers chose a central point within the new county, a location which was platted and named Carollton, to be their county seat.[2]
In Carrollton, the county's citizens successively built three courthouses. The third courthouse, built in 1891−1892, is the Romanesque Revival and Second Empire structure in use today. It is faced with rough-cut stone, surmounted by a mansard roof and clock tower. The cost of the 1892-completed courthouse was $40,231 in the gold-coin money of the day.[3]
Earlier Greene County courthouse structures, which do not survive, were raised in 1821−1822 and 1830−1832.[3]