Randolph County, Illinois: History
Randolph County, organized in 1795, was the second county formed in what ultimately became the state of Illinois, but which was then Illinois Territory after Virginia and Pennsylvania ceded their land claims and the Continental Congress passed the Northwest Ordinance on July 13, 1787. St. Clair County to the north had been formed in 1790 after adoption of the U.S. Constitution, and named after the first Territorial Governor, General Arthur St. Clair, who before his federal appointment, had resided in Pennsylvania. Its name honored former Virginia Governor Edmund Randolph, who as Virginia's governor had ceded that state's land claims allowing the Northwest Ordinance, and later became U.S. Attorney General. General George Rogers Clark and Virginia militiamen with the assistance of Chief Jean Baptiste De Coigne had captured the area from the British on July 4, 1778, near the end of the Revolutionary War. Virginia then administered the vast area, which it had called Illinois County, Virginia after the populated areas of Kentucky County, Virginia south of the Ohio River were admitted to the union as the state of Kentucky, which allowed slavery. However, slavery was not permitted in the Northwest Territory. Moreover, exposure to European diseases, as well as conflict, had decimated the indigenous peoples of the area. After more heavily settled areas in the east had formed first the State of Ohio, the remaining area became the Indiana Territory, and in 1803 territorial governor William Henry Harrison (of a distinguished Virginia family who later became U.S. President) signed a treaty with Chief Jean Baptiste De Coigne representing the Kaskaskia and allied indigenous peoples. After Congress admitted the State of Indiana the remaining land east of the Mississippi had become the Illinois Territory. In 1809 its first Territorial Secretary, former Kentuckian Nathaniel Pope, in his capacity as acting governor, issued a proclamation establishing Randolph as one of the Illinois' two original counties. The county's boundaries were last changed in 1827, when land to the east formed Perry County.
The Mississippi River has played a prominent role in the county's history. The first two capitals of Illinois were Cahokia (declared a town by George Rogers Clark) and Kaskaskia (also captured by Clark and which became the Randolph County seat), and both nearly abandoned after course alterations. In 1881, the flooding Mississippi severed the isthmus that connected Kaskaskia to the Illinois mainland, destroying the original village of and forcing its historic cemetery to be relocated across the river to Fort Kaskaskia. Crains Island, southeast of Chester, is another enclave of Illinois west of the Mississippi that was created by a change in the river's course.