Service Notes:

Hours of Operation: Service at all times
Length of Route: 3.85 miles
Number of Stations: 9 stations
Car Types Assigned: 2200-series, 2600-series (see Car Assignment sheet for latest car assignments)

Brief Description:

Two subway lines included in the Initial System of Subways plan, the State Street Subway and Milwaukee-Dearborn Subway, were designed to accommodate crosstown routes through downtown. The Milwaukee-Dearborn tubes would give the Logan Square branch a more direct route to downtown, entering from the northwest rather than the more circuitous approach from the southwest via the old Metropolitan main line.

Federal dollars made available by President Franklin Delano Roosevelt's New Deal programs during the Great Depression made the construction of the subways possible, allowing Chicago to carry out a civic improvement it'd long planned for but been able to get off the ground. Work in the Milwaukee-Dearborn tubes began in March 1939. Chicago built its subways using the deep bore method. Each subway line has two tubes, one per track in each direction, each dug with its own boring shield twenty-five feet in diameter. Each tunnel was then backed up with continuous steel liner plates and ribs, reinforced with steel bars, and covered with concrete. The only sections constructed by the "cut-and-cover" method were the station mezzanines, crossovers between the tunnels, and short distances just before the subway portals as the tubes ascend to ground level to connect to the elevated.

While the subway was under construction, world events took a critical turn. Completion of the stations was delayed by a materials shortage due to rationing for World War II. Subway Route No. 2 (Milwaukee-Dearborn), which was 80% complete in 1942, was mothballed after the war began due to wartime labor and materials rationing, but Route No. 1 (State Street) was classified as an essential wartime transportation link for defense plant workers and was allowed to continue.

The City would not return to work on the Dearborn Subway for several years, leaving the partially completed tubes mothballed under the city streets. Finally, in late 1945, work resumed on the subway when the city advertised for bids to build the hand-mined western leg of the route.

The Milwaukee-Dearborn Subway officially opened for revenue service after midnight on February 25, 1951 when a train driven by motorman Wallace Hurford left Logan Square at 12:05am and would be the first to be diverted into the new subway rather than via the old Metropolitan Northwest branch.

Important Dates:

• February 25, 1951 - The Dearborn Street Subway opens, connecting the Logan Square and Humboldt Park branches with downtown, terminating at LaSalle/Congress. Only 6000-series cars are in service there. The connector between the Milwaukee Line and Marshfield junction is closed (as are the Division, Chicago, Grand, Lake Street Transfer and Madison stations on it), though the section between the Lake Street "L" and Marshfield is retained for rolling stock moving purposes.
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• February 24, 1989 - The first phase of the new tri-level Clark/Lake station opens. The station connects the "L" (where the Lake-Dan Ryan, Ravenswood and Evanston trains run), the Dearborn Street subway (the O'Hare-Congress-Douglas) and a street-level entrance in the new State of Illinois Center.
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• February 9, 1992 - Grand/Milwaukee is closed in a service revision to close a budget gap.
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• April 13, 1992 - A tunnel under the Chicago River collapses, flooding Loop basements, service tunnels and the CTA subway system. Service is disrupted in the Dearborn Street Subway for 24.
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• June 25, 1999 - The Grand/Milwaukee station, closed in the service revision of 2/9/92, is reopened effective at 6am. Reactivated in response to increasing population around the station, the mezzanine recieves a thorough cleaning and new fare equipment while the platform is given a fresh coat of paint, new signage, and a deep scrubbing.

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