Chicago is a major transportation hub in the United States. It is an important component in global distribution, as it is the third largest inter-modal port in the world after Hong Kong and Singapore. Additionally, it is the only city in North America in which six Class I railroads meet.
Chicago is the largest hub of passenger rail service in the nation. Many Amtrak long distance services originate from Union Station. Such services terminate in New York, Seattle, Portland, New Orleans, San Francisco, Los Angeles, San Antonio, and Washington, D.C. Amtrak also provides a number of short-haul services throughout Illinois and toward nearby Milwaukee, Indianapolis, Saint Louis, and Detroit.
Nine interstate highways run through Chicago and its suburbs. Segments that link to the city center are named after influential politicians, with four of them named after former U.S. Presidents. Traffic reports tend to use the names rather than interstate numbers.
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. The CTA operates an extensive network of buses and a rapid transit elevated and subway system known as the 'L' (for "elevated"), with lines designated by colors. These rapid transit lines also serve both Midway Airport and O'Hare Airport. 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 the few cities in the world (and one of only two American cities) to offer rail service every day of the year for 24 hours around the clock. A new subway/elevated line, the Circle Line, is also in the planning stages by the CTA. Metra operates commuter rail service in Chicago and its suburbs. The Metra Electric Line shares the railway with the South Shore Line's NICTD Northern Indiana Commuter Rail Service, providing 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. Bicycles are permitted on all CTA and Metra trains during non-rush hours and on all buses 24 hours.
Chicago offers a wide array of bicycle transportation facilities, such as miles of on-street bike lanes, 10,000 bike racks, and a state-of-the-art central bicycle commuter station in Millennium Park. The city has a 100-mile (160 km) on-street bicycle lane network that is maintained by the Chicago Department of Transportation Bike Program and the Chicagoland Bicycle Federation. In addition, trails dedicated to bikes only are built throughout the city.
Chicago is served by Midway International Airport on the south side and O'Hare International Airport, the world's second busiest airport, on the far northwest side. In 2005, O'Hare was the world's busiest airport by aircraft movements and the second busiest by total passenger traffic (due to government enforced flight caps). Both O'Hare and Midway are owned and operated by the City of Chicago. Gary/Chicago International Airport, located in nearby Gary, Indiana, serves as the third Chicago area airport. Chicago Rockford International Airport, formerly Greater Rockford Airport, serves as a regional base for United Parcel Service cargo flights, some passenger flights, and occasionally as a reliever to O'Hare, usually in times of bad weather. Chicago is the world headquarters for United Airlines, the world's second-largest airline by revenue-passenger-kilometers and the city is the second largest hub for American Airlines. Midway airport serves as a major 'focus city' for Southwest Airlines, the world's largest low-cost airline.