Within Illinois, nearly all lines either presently have or previously had commuter service in and out of Chicago. Commuter service was eventually discontinued on some lines, while surviving commuter service is now operated by Metra. A few lines serving Indiana also previously had commuter service, now all discontinued. And a few commuter lines previously extended into Wisconsin, with all service in Wisconsin eventually discontinued except to Kenosha.
Beyond commuter territory, stations previously existed in nearly every town which the railroads passed through. On most main lines, intercity passenger trains continued at least until the late 1950's. But mainly from the 1930's through the 1950's, local service was discontinued in many of the smaller towns. Surviving passenger trains stopped only in the larger cities and towns. And on routes retained by Amtrak in 1971, service was discontinued to all except the largest cities.
Known stations are marked, while some station locations in the Chicago area are estimated. A number of stations are identified as "union stations". One often thinks of a "union station" as a large downtown station, such as Chicago Union Station. But a union station is any station, which is shared by multiple railroads. Such stations were often constructed at locations where railroads cross.