Illinois State Route 21 runs north-south through the center of Lake County. The name that this highway carries for it's life it Milwaukee Ave. IL St Rt 21 passes through the following towns in Lake County. Buffalo Grove Riverwoods
Lincolnshire Vernon Hills Libertyville
Waukegan
Gurnee
IL St Rt 21 is multi-plexed in Lake County. U.S. Rt. 45, from the Lake/Cook County Line to Lincolshire.
IL St Rt 21 intersects the following highways in Lake County. Illinois State Route 22, at Lincolnshire.
NB IL St Rt 21 in Vernon Hills. A BGS on WB I-94. A BGS on EB I-94. A junction marker on EB IL St Rt 137. A junction marker on NB U.S. Rt. 41. A junction marker on NB U.S. Rt. 41. The northern end of IL 21 at U.S. Rt. 41 in Gurnee. The northern end marker.
