Here's an overview of the Chicago Transit Authority, both its history and its present-day status as the second largest public transportation system in the United States. The largest mass transit system in America is the MTA in New York.
The rail system is referred to as the "L" because most of its rail lines are elevated above the city streets.
On any weekday, 1.6 million rides are taken on the CTA (buses and the "L").
There are 1,864 buses, 129 routes and 10,768 posted bus stops. Average weekday ridership was 826,322 in 2016.
There are 1,492 rail cars, eight different routes and 145 train stations. Average weekday ridership was 759,866 in 2016.
The rapid transit system provides transportation to both of Chicago's major airports, O'Hare and Midway.
CTA has K-9 patrol units in addition to police security.
Random screenings are performed by the CPD Mobile Explosives Screening Team.
There are more than 23,000 surveillance cameras.
November 24, 1936 - Eleven people are killed and many more are injured when two trains collide at the Granville Avenue station.
October 17, 1943 - The State Street Subway opens.
October 1, 1947 - CTA begins operating, taking over routes formerly serviced by the Chicago Rapid Transit Company and the Chicago Surface Lines.
November 5, 1956 - Two trains crash at the Wilson Avenue station, killing eight, and injuring nearly 200.
June 21, 1958 - Streetcar service ends.
February 4, 1977 - Four train cars swerve off the elevated tracks and fall to the street below. Eleven people are killed and more than 160 are injured.
September 3, 1984 - The CTA introduces rail service to O'Hare International Airport.
February 21, 1993 - The CTA renames all of its rail lines, using colors to identify different routes.
October 31, 1993 - The CTA introduces rail service to Midway International Airport.
August 18, 1997 - Fare cards are first used.
June 1, 1999 - Use of tokens is discontinued.
June 25, 2006 - The Pink Line opens.
February 7, 2010 - Service cuts are implemented and fares increase to close a budget gap. More than 1,000 workers are laid off during the month of February.
March 24, 2014 - A Blue Line train derails at the O'Hare International Airport station, smashing through a barrier at the end of the tracks and careening up an escalator, injuring more than 30 people. A transit union spokesman tells the Chicago Tribune that driver fatigue likely caused the accident.
July 1, 2015 - The CTA introduces a new payment method called the Ventra fare system, with reloadable cards that are tapped to enter turnstiles.