Transit systems thumb|upright=1.2|Chicago Union Station, opened in 1925, is the third-busiest passenger rail terminal in the United States. The Regional Transportation Authority (RTA) coordinates the operation of the three service boards: CTA, Metra, and Pace. The Chicago Transit Authority (CTA) handles public transportation in the City of Chicago and a few adjacent suburbs outside of the Chicago city limits. The CTA operates an extensive network of buses and a rapid transit elevated and subway system known as the Chicago "L" or just the "L" (short for "elevated"), with lines designated by colors. These rapid transit lines also serve both Midway and O'Hare Airports. The CTA's rail lines consist of the Red, Blue, Green, Orange, Brown, Purple, Pink, and Yellow lines. Both the Red and Blue lines offer 24‑hour service which makes Chicago one of a handful of cities around the world (and one of two in the United States, the other being New York City) to offer rail service 24 hours a day, every day of the year, within the city's limits. Metra, the nation's second-most used passenger regional rail network, operates an 11-line commuter rail service in Chicago and throughout the Chicago suburbs. The Metra Electric Line shares its trackage with Northern Indiana Commuter Transportation District's South Shore Line, which provides commuter service between South Bend and Chicago. Pace provides bus and paratransit service in over 200 surrounding suburbs with some extensions into the city as well. A 2005 study found that one quarter of commuters used public transit."New Yorkers are top transit users" , by Les Christie,CNNmoney.com, June 29, 2007. Retrieved September 21, 2009.
Transit systems thumb|upright=1.2|Chicago Union Station, opened in 1925, is the third-busiest passenger rail terminal in the United States. The Regional Transportation Authority (RTA) coordinates the operation of the three service boards: CTA, Metra, and Pace. The Chicago Transit Authority (CTA) handles public transportation in the City of Chicago and a few adjacent suburbs outside of the Chicago city limits. The CTA o,perates an extensive network of buses and a rapid transit elevated and subway system known as the Chicago "L" or just the "L" (short for "elevated"), with lines designated by colors. These rapid transit lines also serve both Midway and O'Hare Airports. The CTA's rail lines consist of the Red, Blue, Green, Orange, Brown, Purple, Pink, and Yellow lines. Both the Red and Blue lines offer 24‑hour service which makes Chicago one of a handful of cities around the world (and one of two in the United States, the other being New York City) to offer rail service 24 hours a day, every day of the year, within the city's limits. Metra, the nation's second-most used passenger regional rail network, operates an 11-line commuter rail service in Chicago and throughout the Chicago suburbs. The Metra Electric Line shares its trackage with Northern Indiana Commuter Transportation District's South Shore Line, which provides commuter service between South Bend and Chicago. Pace provides bus and paratransit service in over 200 surrounding suburbs with some extensions into the city as well. A 2005 study found that one quarter of commuters used public transit."New Yorkers are top transit users" , by Les Christie,CNNmoney.com, June 29, 2007. Retrieved September 21 2009.