Although the work on the station under Dearborn Street began in March 1939, the construction of the Milwaukee-Dearborn Subway and the station was suspended in 1941 because of wartime material shortages. Therefore commuters had to wait ten years for the station to open. Monroe opened on February 25, 1951, fourteen years after being ordered by the Chicago Rapid Transit Company in 1937.
In 1969, the stairs to the northwest corner of Dearborn Street and Monroe Street were closed to permit the construction of the First National Bank Building and Plaza (renamed the Chase Tower) after the completion of a new entry was added in the lower level of the tower to the station. Monroe station was completely refurbished in 1982, but was not designed to be accessible to the handicapped.