Roads of the Mid-South & West > Highways of the State of Illinois > Illinois State Routes 101-199 > Illinois State Route 166
| Illinois State Route 166 |
Illinois State Route 166 is a north-south highway in Southeastern Illinois. This runs from Illinois State Route 13, near Pittsburg, to U.S. Rt. 45, at New Burnside. Info on IL St Rt 166 is broken down by county below.