Grafton is the oldest city in Jersey County, Illinois, United States. It is located near the confluence of the Illinois and Mississippi Rivers. The population was 609 at the 2000 census, and the population was 725 in the 2008 official US Census estimate. Prior to the Great Flood of 1993, Grafton had enjoyed a stable population of nearly 1,000 residents. The city's current mayor is Tom Thompson. Grafton is a part of the Metro-East region and the St. Louis Metropolitan Statistical Area.