Chicago's first railroad, the Galena & Chicago Union, began building westward from Chicago in 1848, through Turner Junction (now West Chicago) to Rockford and Freeport. That railroad later became part of the Chicago & North Western and (in the 1990's) the Union Pacific.
G&CU constructed this large wooden passenger station in Marengo, a few miles west of Union, in 1851. One end of the depot held a passenger waiting room, while the other was used for baggage and freight. Passenger service to Marengo ended in 1950, but the depot remained in use for freight until the mid-1960's.
IRM purchased the station from C&NW in 1967. The structure was divided into two large sections and moved by truck to IRM, where it was reassembled. The station exterior is largely unchanged, but inside, restrooms have been installed in the baggage area.
It is the oldest station in continuous service west of Pittsburgh.