From Bridgeport, services reach Chicago Union Station via Canadian National's Freeport Subdivision.

Illinois governor Joel Matteson believed the success of the venture depended on it becoming the Chicago extension of the existing Chicago, Alton and St. Louis Railroad from Joliet, and hired that railroad to first survey, and then to build the new line.

[3] In the 20th century, the subdivision progressively came under the control of larger railroads due to mergers.

In 1987, most of the former Alton Railroad route, from Joliet to St Louis, was purchased by the newly formed Chicago, Missouri and Western Railway, leaving only the Joliet Subdivision with the Illinois Central.

[4] Finally, in 1998, the subdivision passed under the control of the Canadian National Railway, together with the rest of the Illinois Central.