Illinois State Route 56 runs east-west in Southern St. Clair County. It runs from Illinois State Route 13, near New Athens, to the St. Clair/Monroe County County Line, near Hecker. IL St Rt 156 does not pass through any towns in St. Clair County. IL St Rt 156 is mutli-plexed in St. Clair County. Illinois State Route 159, near Hecker.
IL St Rt 156 intersects the following highways in St. Clair County. Illinois State Route 159, near Hecker.
WB IL St Rt 156/SB IL St Rt 156 north of Hecker. WB IL St Rt 156 northeast of Hecker. A St. Clair County mile marker. WB IL St Rt 156 west of New Athens. A junction marker on WB IL St Rt 13. EB IL St Rt 156 near IL St Rt 13. The eastern end marker.
