While the transit system would remain largely the same for over sixty years after, that does not mean that improvements for passengers' benefits stopped. Quite the opposite, in fact. It was during this time that the "L" made some of its best improvements, many surviving today. One thing that Charles Tyson Yerkes had advocated that would help the transit riders of Chicago was the unification of the various "L" companies. Several attempts were made to do this and by 1911, this was indeed achieved to some measure, though no thanks to Yerkes, who'd overstayed his welcome in Chicago by the opening of the Northwestern "L" and since left town. Instrumental in this was Samuel Insull, a utilities magnate who'd taken an interest in transportation. Under Insull and others, the Chicago Elevated Railways Collateral Trust (CER) brought together all four "L" companies, although separate company identities were still maintained. It was under the CER that many important changes were made. In 1913, the first trains were through-routed for crosstown trips, the first of which was from Jackson Park on the south side to Linden Avenue in Wilmette. Ravenswood-Kenwood trips were inaugurated the same year, as well as Wilson Avenue-Englewood Expresses. A system of universal transfers was also first instituted under the CER, eliminating the need for an extra fare if switching to any "L" line's train. The Lake Street Transfer station was also created where the Met and Lake Street "L"s cross at Lake and Paulina Streets for this purpose. In 1919, thanks to Sam Insull, who also owned several interurban lines, his Chicago, North Shore and Milwaukee line began operations into the loop through the Northwestern Elevated. Passengers could now board a train in downtown Chicago and ride all the way to Milwaukee, Wisconsin without changing trains! This service continued until the line's abandonment in 1963. From 1922 until 1938, the North Shore line trains operated all the way to the Jackson Park terminal.
In 1924, Samuel Insull realized that for the sake of the "L"'s continued longevity, it would have to be completely consolidated, with all the companies officially merging into one. The Chicago Rapid Transit Company (CRT) accomplished this and under the CRT, the "L"'s service continued to grow. When Insull's North Shore Line created an extension into Niles Center (later, Skokie), his "L" reaped its benefits as well. The "L" operated local service from Howard Street to Dempster in Niles Center, making seven stops in Evanston and Skokie along the way. This service was continued until 1948, when the successor Chicago Transit Authority replaced the service with buses. Another of Insull's interurban's was given access to the "L" and vice-versa; in 1925, the "L" began operations on its Garfield Park Line all the way into the far western suburb of Westchester, eventually to a terminal at Mannheim & 22nd in 1930. Platforms in the Loop were also extended for greater accommodation of passengers under the CRT's reign. The "L", at the height of its service (reached under the CRT when it opened the Westchester Line) embraced 227.49 miles of track, carried an average of 627,157 passengers per weekday, operated 5,306 scheduled trains in the same time period, and had 227 stations in the Chicago metropolitan area.
Chicago had been proposing and trying to get subways built in the city since the turn of the century. None of the proposals ever got beyond the planning stage due to the enormous costs involved. None, that is, until, President Franklin Delano Roosevelt made federal money available for such public works projects. In 1937, Chicago's applications for grants and loans for a subways were approved. When ground was broken in 1938, two tubes were to be built: one under State Street and another under Dearborn Street. The subway was never meant to replace the Loop, but supplement it, as it was getting rather congested with the increased traffic. The Evanston/Skokie/Howard trains were to through-routed under State Street to the south side. The Logan Square Branch was to continue under Milwaukee Avenue, connecting to the Dearborn tunnel and ultimately turn west to meet the Garfield and Douglas Park Branches of the line. The Ravenswood and Lake Street lines would stay on the Loop. Construction was difficult due to the wet clay that lays underneath the city and work on the Dearborn tunnel was halted by World War II. When the State Street tunnel did open in October, 1943 and the Dearborn in 1951, they sported some special features for the benefit of the traveling public. The stations had an excellent ventilation system, the first use of fluorescent lighting in a subway, escalators and turnstiles. Another unique feature was the single, extra-long platforms in each tube that accommodated several stations; State Street's extends 3,300 feet from one end to the other (a Guinness Book record), while Dearborn's is 2,500 feet. The track was equipped with a special "block" signal and interlocking system for spacing and emergency stopping of trains, as well as a drainage pumping system to keep water out of the tubes. More subways were planned for Chicago as well; none ever came to light.
Subway Photo: A view down the 3500 foot island platform in the State Street subway shortly after its opening in 1943. In the distance and stopped on the other track (visible on the right side of the picture) are 4000-series trains. (Photo by the Peter Fish Studios)