Initially known as the Douglas Park branch, construction began in June 1893 and the line was inaugurated on April 28, 1896 between Marshfield Avenue and. The branch started off with four stations and was the shortest of the Metropolitan West Side Elevated. Construction time was longer than in other sections. On August 7, 1896, the Douglas Park branch was extended to. On June 29, 1900, the City of Chicago approved an extension of the branch to and construction took place in mid-June 1901. On March 10, 1902, the Douglas Park branch was extended to Lawndale Avenue, which allowed the opening of four new stations:,, Homan, and Clifton Park. On May 22, 1907, the Douglas Park branch was extended to 46th Avenue, which is the Chicago city limits. The station was a few meters from the Hawthorne plant of the Western Electric which was one of the largest employers in the area of Chicago at the time. On December 16, 1907, the Douglas Park branch was extended to , extending service to the town of Cicero, Illinois. On August 20, 1910, the Douglas Park branch was extended to . On August 1, 1912, service was extended to 56th Avenue and extended again to Lombard Avenue exactly three years later. The final stretch on the branch was to Oak Park Avenue, in Berwyn, which opened on March 16, 1924. On December 9, 1951, during the establishment of skip/stop A/B, the Chicago Transit Authority l, which had taken over operation of the "L" system in 1947, streamlined service on the line and shut down five stations: 14th Place, Homan, Drake, Lawndale and Kenton, while opening a station at. On February 3, 1952, service on the Douglas line was suspended to all stations west of. Service to these areas was replaced by a bus route. The stations at Roosevelt and Douglas Park were closed three months later. On June 22, 1958, Douglas trains were rerouted to the West-Northwest route, the Congress branch, the new line in the middle of the Eisenhower Expressway and connecting routes to the Milwaukee-Dearborn Subway, heading north to. The new system changed the service and it was decided that all stations on the Douglas branch would now be "B" and the Congress branch would now be "A". In 1973, due to budget cuts, the 50th Avenue station closed.
Renovations
In 1983, and were rebuilt to make them ADA accessible for passengers with disabilities. The poorly utilized station was closed to accelerate service the following year. In 1993, was rebuilt to provide access for passengers with disabilities and the CTA color-coded the lines, placing the Douglas branch as part of the Blue Line. In 1995, the A/B service was abandoned and all trains stop at every station, does not affect the service of the stations on the Douglas branch. In 1996, the CTA changed the name of the branch to the Cermak branch, although Chicagoans still use the name "Douglas" to refer to the line. In 1998, the branch lost its 24-hour service, along with the Purple and Green lines. On September 10, 2001, the CTA began a $363 million renovation project of the branch which was completed on January 8, 2005. As of today, all eleven stations on the branch are ADA accessible.
Current
The current Pink Line route was assigned to the Douglas branch on June 25, 2006. The CTA ended Blue Line service on the Douglas branch on April 25, 2008.
