Originally named Chicago Air Park, Midway Airport was built on a 320-acre (1.3 km2) plot in 1923 with one cinder runway that primarily servedairmail services. In 1926 the city leased the airport for commercial purposes. The airport was designated as Chicago Municipal Airport on December 12, 1927. By 1928 the airport had twelve hangars and four runways, lit for night operations.
In 1931 a new passenger terminal opened at 62nd St; the following year the airport claimed to be the "World's Busiest" with over 100,846 passengers on 60,947 flights. The March 1939 OAG shows 47 weekday departures: 13 on United, 13 American, 9 TWA, 4 Northwest and two each on Eastern, Braniff, Pennsylvania Central and C&S. New York's airport (Newark, then LaGuardia by the end of 1939) was then the busiest airline airport in the United States, but Midway passed LaGuardia around 1948 and retained the title until O'Hare claimed it in 1961.
More construction was funded in part by $1 million from the Works Progress Administration; the airport expanded to fill the square mile in 1938–41 after a court ordered the Chicago and Western Indiana Railroad to reroute tracks that had crossed the square along the north edge of the older field.
In July 1949 the airport was renamed after the Battle of Midway. That year Midway saw 3.2 million passengers; passengers peaked at 10 million in 1959. The diagram on the January 1951 C&GS instrument approach chart shows four parallel pairs of runways, all 4240 ft or less except for 5730-ft runway 13R and 5230-ft runway 4R. Airport diagram for 1959
The April 1957 OAG shows 414 weekday fixed-wing departures from Midway: 83 American, 83 United, 56 TWA, 40 Capital, 35 North Central, 28 Delta, 27 Eastern, 22 Northwest, 19 Ozark, 11 Braniff, 5 Trans-Canada and 5 Lake Central. Air France, Lufthansa and REAL (of Brazil) had a few flights a week. Midway was running out of room and in any case could not handle the 707 and DC-8 jetliners that appeared in 1959; every Chicago jet flight had to use O'Hare, which had opened to the airlines in 1955. Electras and Viscounts could have continued to fly out of Midway, but O'Hare's capacious new terminal opened in 1962, allowing airlines to consolidate their flights. From July 1962 until the 727 appeared in July 1964 Midway's only scheduled airline was Chicago Helicopter. In August 1966 a total of four fixed-wing arrivals were scheduled, all United.
Post-O'Hare reconstruction (1963–1993) 
By 1967, reconstruction began at the airport, adding three new concourses with 28 gates and three ticket counters, and in 1968 the city invested $10 million in renovation funds. The funds partly supported construction of the Stevenson Expressway, which proved to be a major route for passengers to the airport, and Midway saw the return of major airlines during that year, serving 1,663,074 passengers on jets such as the McDonnell Douglas DC-9, Boeing 727, and Boeing 737 that could use Midway's runways, which the Boeing 707 and Douglas DC-8 could not.
In 1979 Midway Airlines began operations, the first to do so after the Airline Deregulation Act of 1978, and became the flagship carrier at Midway until it ended operations in 1991. Midway Airlines helped revitalize the airport and led the way for other discount carriers, who benefited from Midway's lower costs and close proximity to Chicago's Loop, to prosper. Southwest Airlines, which began operations at Midway in 1985, was one such beneficiary. Three years earlier, in 1982, the City of Chicago purchased Midway Airport from the Chicago Board of Education for $16 million.
The Chicago Transit Authority displaced the original location of the Carlton Midway Inn to open a new CTA terminal at the airport on October 31, 1993, for the newly established Chicago 'L' Orange Line, which connected Midway to Chicago's Loop. The CTA's Orange Line connects Midway todowntown Chicago via elevated train transportation. Midway Airport is the terminus of the line, which traverses the southwest portion of the city before ending in the Loop and cycling back to Midway again. The Orange Line does not run 24 hours a day (unlike the Blue Line, which provides 24-hour service to O'Hare and the Red Line), but does operate extensive hours from about 4:00 am to 1:00 am, running at an average of 8-minute intervals. The train journey from Midway Airport to the Loop takes 25 minutes.
Years of ATA (1994–2008) 
In 1996, after failing to get his Lake Calumet Airport and having received harsh criticism for the idea of turning the airport into an industrial park, ChicagoMayor Richard M. Daley announced the Midway Airport Terminal Development Program, which was launched the following year. At the time, it was the largest public works project in the state. The Midway Airport parking garage opened in 1999, bringing covered parking to the airport for the first time. The garage is connected to the Midway terminal building for convenient access to ticket counters and baggage claim areas.
Continuing with the expansion project, a pedestrian bridge over Cicero Avenue was constructed in 2000 connecting the new terminal to the new concourses. In 2001, the new 900,000-square-foot (84,000 m2) Midway Airport terminal building opened, offering expanded ticket counters, spacious baggage claim areas, traveler information and a short walking distance to airline gates. A 50,000-square-foot (4,600 m2) food court opened with Chicago-style food and retail options.
In 2002, Midway welcomed the return of direct international service after a 40-year absence with the opening of the new Federal Inspection Service facility in Concourse A.
In June 2004, Mayor Daley and airline officials celebrated the completion of the Terminal Development Program. The expansion project, designed byHNTB resulted in the addition of 14 gates (from 29 to 43), with the airport now providing 43 gates on 3 concourses. A new 6,300-space economy parking garage, including a new bridge and roadway used exclusively for buses shuttling passengers to and from the terminal, opened in December 2005.
Simultaneous to Midway's expansion, ATA Airlines began rapid expansion at Chicago Midway in the early 2000s (decade), and prior to 2004, was the airport's dominant carrier, occupying and operating 14 of the 17 gates in Concourse A. However, after the airline declared bankruptcy in October 2004, scheduled service from Midway significantly decreased.
For over 16 years, Midway had been the main hub for Indianapolis-based ATA, but the airline shut down on June 7, 2008 before the airline filed for bankruptcy in April 2008, immediately discontinuing all flights. On April 3, 2008, ATA Airlines discontinued all operations.
In November, 2008, Porter Airlines, which flies between Midway and Toronto, Canada, was the only international route served from Chicago–Midway after ATA Airlines, which had flights to Mexico, ceased operations in April that year. On December 13, 2010, a second carrier, Volaris, began flights between Guadalajara and Midway.
Years after ATA (2009–) 
On April 20, 2009, a $2.5 billion deal to privatize the airport via a 99-year lease fell through when the consortium could not put together financing. The City is to keep $125 million in the downpayment. The consortium operating under the name of Midway Investment and Development Company LLC consisted of Vancouver Airport Services, Citi Infrastructure Investors and Boston's John Hancock Life Insurance. It was awarded the contract in October 2008 by the City Council which voted 49–0 to approve it. The consortium would have operated the airport and collected airport parking, concession and passenger facility charges. However, Chicago would have continued to provide fire and police services. Chicago privatized the Chicago Skyway in 2007.
Starting in early 2009, a construction project added a new walkway and food court to Concourse A. The project also connected gates A4A and A4B to the main A concourse. Expansions were completed in the spring of 2010.
Today, Southwest Airlines is the largest airline serving Midway with 225 daily flights. Midway is also Southwest's largest focus city. Southwest pilots expressed concern about the control tower closure between the hours of 1 a.m. and 6 a.m. due to 2013 Federal budget sequester as it will impact red-eye flights to the west coast and diversion to other airports.
Chicago Midway Airport is the second largest passenger airport in the state of Illinois after Chicago O'Hare International Airport. In 2005, Chicago Midway International Airport was the 30th busiest airport in the United States in terms of passenger traffic.
Chicago Midway ranked highest in customer satisfaction among medium-sized airports (10 million to 30 million passengers per year) in J. D. Power and Associates' 2008 study.
Southwest, along with their subsidiary AirTran Airways, is the dominant carrier at Midway, controlling 34 of the airport's 43 gates. Currently, the airlines offer a combined 250 daily departures to 60 nonstop destinations.[26