Illinois State Route 31 runs north-south in Eastern Mc Henry County. This runs from the Kane/Mc Henry County Line, at Algonquin, to U.S. Rt. 12, at Richmond. IL St Rt 31 passes through the following towns in Mc Henry County. Algonquin
NB IL St Rt 31 at the Kane/Mc Henry County Line. NB IL St Rt 31 in Algonquin. NB IL St Rt 31 at Main Street in Algonquin. NB IL St Rt 31 at IL St Rt 62. NB IL St Rt 31 near James Rakow Road. A Mc Henry County mile marker. NB IL St Rt 31 south of U.S. Rt. 14. NB IL St Rt 31 at U.S. Rt. 14. SB IL St Rt 31 at U.S. Rt. 14. A guide marker on EB U.S. Rt. 14. NB IL St Rt 31 north of Crystal Lake. NB IL St Rt 31 south of Prairie Grove. NB IL St Rt 31 north of Prairie Grove. NB IL St Rt 31 south of Bull Valley Road. NB IL St Rt 31 near Mc Cullom Lake Road. A guide marker on NB IL St Rt 31. NB IL St Rt 31 north of Alexander Blvd. NB IL St Rt 31 south of Ringwood. A junction marker on SB U.S. Rt. 12. The northern end of IL St Rt 31. The northern end marker of IL St Rt 31. (April, 2022)
