With all cars in married pairs, all trains use an even number of cars. The maximum train length is 8 cars on most lines, 6 cars on the Purple Line, and normally 2 cars on the Yellow Line.
In 1961, the CTA adopted one person operation during slack periods on the Evanston line. A group of single unit cars, numbers 1-50, had been delivered from St. Louis Car, supplementing the married pair 6000's constructed by St. Louis Car through the 1950's. These single unit cars also had fare boxes at the cabs, also enabling fare collection by the motormen at unattended stations. This practice was eliminated in 1985.
The Skokie Swift service began in 1964, using some of the 1-50 series cars reequipped with pantographs. One person operation was especially feasible on this line, with its short trains and nonstop operation. During the rush hours, these single unit cars were supplemented by articulated train sets 51-54, renumbered from 5001-5004. In 1985 and 1986, 51-54 were replaced with 2 car sets 61-64, modified and renumbered from 1-50 series cars. An additional set 65 was created in 1990. All of these cars were replaced by 3200 series cars in 1993.
Also in 1993, the CTA began a program to phase in one person operation over the entire rapid transit system. The motorman would now be known as an "operator". The new 3200 series cars from Morrison-Knudsen were built with full width cabs designed for one person operation, so that the operator would be able to operate the doors on both sides of the train. The Orange Line opened that year, using one person operation and 3200 series cars. 3200 series cars also went to the Brown Line, where conductors were eliminated in 1995. For a while, a "collector" would be on board Brown Line trains during certain slack periods, when many stations would remain unattended.
As conductors were being eliminated from the trains, stations eventually became attended during all hours of operation, eliminating all need for fare collection on the trains. Conductors were virtually eliminated on all remaining lines in 1997, with older cars modified for one person operation. However, conductors were retained for a while for the subway portions of the Red Line and Blue Line when 6 or 8 car trains are operated. In addition, certain stations with curved platforms originally had employees working there to insure that all cars are observed as doors are opened or closed. But those employees were replaced with closed circuit TV systems at those stations.
With the elimination of conductors, announcements would be made by the operator. In the year 2000, the live operator announcements were replaced with automated recorded announcements.
The first women were hired for rapid transit service in 1974.
The CTA first used color names for its routes in 1993, when the two south side lines traded places and the line to Midway Airport was opened. New roller signs were in the appropriate new colors, but signs continued to use the traditional route names. With the reopening of the Green Line in 1996 after the two year renovation project, new roller signs were introduced which indicate the actual destination. Signs would thus be changed as the trains turn back. Similar destination signs were gradually introduced on the other lines. The traditional route names have thus been official dropped, with the colors now used as the official route names.