In the early 1900's, a series of interurban railroads were consolidated by businessman William B. McKinley into the Illinois Traction System (ITS), an affiliate of the Illinois Power and Light Company. The Illinois Traction System, at its height, provided electric passenger rail service to 550 miles of tracks in central and southern Illinois.

The system's Y-shaped main line stretched from St. Louis to Springfield, Illinois, with branches onward from Springfield northwest to Peoria and eastward to Danville. A series of affiliated street-level city trolley lines provided local passenger service in many of the cities served by the main line.

The longest-lived segment was at East St. Louis area of the line descended from an Edwardsville-Alton interurban line bought by the Illinois Traction System in 1928. Because the Illinois Traction System traversed some towns on street trackage with very tight turns, freight operation required the use of short trains and special hardware.

New bypass trackage was constructed around some towns for freight operation to partially solve this problem. Springfield was an example of this. In a few other towns, arrangements were made with a parallel steam railroad for trackage rights in order to provide a bypass.

An example of difficult town running (for the town as well as the railroad) was at Morton, Illinois, just east of Peoria, where a heavy duty well maintained track with trolley catenary suddenly found itself running down the center of the town's brick paved main street.

The company became the Illinois Terminal Railroad Company in 1937.