The Illinois, Iowa & Minnesota Railway was created in 1904 and built a line north from a connection with the Milwaukee Road at Delmar that ended at East Joliet. In 1905, a second line was built from Aurora to Rockford. The construction of this line sparked a protest among residents in Rockford because of increased railroad tariffs imposed to support it; at the time, there was already more than one railroad operating between Rockford and Chicago, and the residents felt yet another railroad line was unnecessary.
The two lines of the II&M were separated between East Joliet and Aurora, so trackage rights were sought between these two points on the EJ&E, thus giving the II&M a whole route that ran in a generally northwest-southeast direction. In 1908, the II&M was renamed the Chicago, Milwaukee & Gary Railway (which is a misnomer, since the railroad never actually visited any of its namesake towns). The CM&G was leased to the Milwaukee Road in 1922, who purchased the entire railroad outright in May of 1930, and subsequently abandoned the northern-most section of track between Rockford and Kirkland. While under Milwaukee Road, the line was primarily used to transfer coal from the mines of central & southern Indiana to the Milwaukee Road mainline for powering steam locomotives, etc.
The line between Dekalb and Aurora was abandoned by the Milwaukee Road in 1947, effectively splitting the former CM&G line in two. The southern section was still accessible through extended trackage rights on the EJ&E, but was abandoned entirely on July 17, 1978; by this time, it was used seldom and for local way freight only, with light interchange with the EJ&E. The final existing segment of the former CM&G, between Kirkland and Dekalb, was abandoned on April 15, 1980, essentially removing the last physical manifestation of the Gary Line.
A crude time line of the route is shown below, running from north to south.
EJ&E Trackage Rights--> |-------------|
Rockford --- Kirkland ---- Dekalb ---- Aurora xxxxxxxx East Joliet --- Delmar
===================================================================================
1904 |----- Built -----|
1905 |---------- Built --------------------|
1908 |-------- Renamed to Chicago, Milwaukee & Gary Railroad --------------|
1922 |--------------- Leased by Milwaukee Road ----------------------------|
1930 |--abandoned--|------- Purchased by Milwaukee Road -------------------|
1947 |-abandoned-|
1978 |-- abandoned ----|
1980 |-abandoned-|
Little evidence is left of this railroad line today. In Rockford, the original concrete slabs that supported the line over the Rock River are still visible in the water. Topographical maps suggest that Belt Line Road between the river and Route 251 may be sitting atop the abandoned railbed in the southern part of the city.