Both of Illinois Route 148's termini branch from Route 37, the north terminus at Mount Vernon, and the southern terminus just north of Pulley's Mill.

Originally connecting Effingham to Cairo, it was a heavily-traveled highway before Interstate 57 was opened.

Illinois 37 was long a part of the most direct route between Chicago and Memphis.

Illinois 37 has become a route of local significance instead of the busy, long-distance, inter-city highway that it was until the 1970s.

As a town-to-town route, it especially serves communities which have no access to Interstate 57.