It is possible that 1848 was the first year when people commuted into Chicago by train. The Galena & Chicago Union Railroad opened in 1848, originally between Chicago and Oak Park, and was Chicago's first railroad. The railroad never actually reached Galena, and soon became part of the Chicago & North Western Railroad. C&NW was absorbed by Union Pacific in 1995, and UP continues to actually operate the commuter trains.

Chicago's first real commuter railroad was the Illinois Central Railroad, which began operating on July 21, 1856, with 4 daily round trips between Chicago and a new suburb known as Hyde Park. The first trip carried no passengers. Paul Cornell, a real estate developer in the area, sold land to IC to build the railroad, under the condition that IC introduce the commuter service. Such a commuter rail service would make Cornell's property attractive to buyers. Hyde Park was annexed to the city of Chicago in 1889, and IC electrified its commuter service in 1926.

Commuter service was established on other area railroads, as they were built, and the service remained rather stable throughout the years. Mostly during the 1950's, the steam railroads converted to diesel operation.

In 1950, the Burlington Route was Chicago's first commuter railroad to introduce bilevel commuter cars. And in 1955, the Chicago & North Western introduced bilevel cars. Bilevel cars were originally steam heated, and the Burlington cars continued to be steam heated until 1973 and 1974. But in the late 1950's the Chicago & North Western launched an ambitious program to modernize its commuter service. C&NW was the first commuter railroad to adopt head end power for cars, with electric heating, and was the first railroad to adopt push pull operation. And unlike the other commuter railroads, C&NW discontinued many of its local stops in Chicago, where paralleling CTA operations existed. With these cost cutting measures, the C&NW service was able to be profitable during much of the 1960's and early 1970's.

With its head end powered bilevel cars and push pull operation, C&NW set a trend which was adopted by all other commuter railroads as they began their modernization programs. In 1961, the Milwaukee Road introduced its first bilevel commuter cars, with modernization completed in 1964. And the Rock Island Railroad acquired 20 bilevels in 1965, and 10 more in 1970. But the Rock Island was financially less healthy than the other railroads. And most of the Rock Island rush hour commuter trains continued to use the "Al Capone" cars from the 1920's. The Rock Island replaced its various older locomotives with some E8 and E9 locomotives acquired second hand from Union Pacific in 1969. But complete modernization of the Rock Island had to wait.

By the late 1960's and early 1970's, the commuter railroads were no longer able to afford expenditures for capital improvements. The Illinois Central needed to replace its venerable 1926 electric cars. The Burlington Route needed to modernize its E9 locomotives and steam heated bilevels, and acquire additional bilevels to accommodate increased ridership. And the Milwaukee Road needed newer more powerful locomotives to replace the FP7 and F9 locomotives, and additional equipment to accommodate increased ridership. So the suburbs along those lines formed "Suburban Mass Transit Districts", which would acquire new equipment using public money. The Burlington equipment was rebuilt with head end power and electric heating. And 20 out of the 25 new Burlington cars were equipped with control cabs. Prior to then, only 6 cars had cabs, requiring the turning of locomotives for most commuter trains.

In 1974, with the railroads losing money on the commuter trains, and other transit systems losing money, the Regional Transportation Authority (RTA) was formed. The RTA subsequently signed purchase of service agreements with the various railroads. The railroads would then continue to operate the commuter trains, subsidized by the RTA and operating according to RTA standards. The Rock Island line was finally completely modernized, with new bilevel cars and F40PH locomotives, and rebuilding of track which had badly deteriorated. And the two rush hour only commuter operations in Illinois, the Norfolk & Western (now Southwest Service), and the former Gulf Mobile & Ohio (now Heritage Corridor), received new bilevel cars and F40PH locomotives, replacing former long distance equipment previously provided by those railroads for use on those lines. At that time, frequencies on those rush hour operations were doubled from one to two daily round trips.

The Chicago & North Western had developed a modern and comfortable commuter rail service on its own. But no money was invested in new commuter locomotives. Rather, older F7 and E8 locomotives were kept operating through rebuilding. But the RTA and Metra enabled the C&NW locomotives to finally be replaced with new F40PH locomotives. And the former Burlington E9 locomotives were finally replaced in 1992.

During the 1980's the RTA was reorganized, and Metra became the name by which the commuter rail system would be known. And Metra assumed direct operation of most commuter lines, with only the Union Pacific (formerly Chicago & North Western), and the Burlington Northern Santa Fe (originally the Burlington Route) continuing to operate their lines under purchase of service agreements.

In 1996, Chicago's first commuter rail line in 70 years opened between Chicago and Antioch, via the Wisconsin Central Railroad, known as the North Central Service. Initial service was primarily rush hour only, over a single track railroad. In 2006, commuter line extensions would be opened to the towns of Elburn and Manhattan. In addition, double track expansions would enable the Southwest Service and the North Central Service lines to become full service Metra lines.