Chestnut is a census-designated place in Aetna Township, Logan County, Illinois. As of the 2010 census, its population was 246. The community is located northwest across the railroad tracks along Illinois Route 54 at Dauphin Street. Its claim to fame, for the sake of town promotion, is that it is the geographic center of the state. A small monument to this effect has been erected in a park near the southwest corner of Melvin Street and East Olive street.