O'Hare International Airport in the context of Itasca, Illinois

SOM, an initialism of its original name Skidmore, Owings & Merrill LLP, is a Chicago-based architectural, urban planning, and engineering firm. It was founded in 1936 by Louis Skidmore and Nathaniel Owings. In 1939, they were joined by engineer John O. Merrill. The firm opened its second office, in New York City, in 1937 and has since expanded, with offices in San Francisco, Los Angeles, Washington, D.C., London, Melbourne, Hong Kong, Shanghai, Seattle, and Dubai.

Notable for its role as a pioneer of modernist architecture in America and for its groundbreaking work in skyscraper design and construction, SOM has designed some of the world's most significant architectural and urban projects including several of the tallest buildings in the world: John Hancock Center (1969, second tallest in the world when built), Willis Tower (1973, tallest in the world for almost twenty-five years), One World Trade Center (2014, currently the seventh tallest in the world), and Burj Khalifa (2010, currently the world's tallest building). The firm's notable current work includes the new headquarters for the Walt Disney Company, the global headquarters for Citigroup, Moynihan Train Hall and the expanded Penn Station complex, and the restoration and renovation of the Waldorf Astoria in New York City; airport projects at O'Hare International Airport, Kansas City International Airport, and Kempegowda International Airport; urban master plans for the Charenton-Bercy district in Paris, New Covent Garden in London, Treasure Island in San Francisco, the East Riverfront in Detroit; P.S. 62, the first net-zero-energy school in New York City; and the design of the Moon Village, a concept for the first permanent lunar settlement, developed with the European Space Agency and Massachusetts Institute of Technology.

O'Hare, located on the far north side of Chicago, is one of the city's 77 community areas. O'Hare International Airport is located within the boundaries of this community area. This community area is the only one that extends outside Cook County; the western edge (an area comprising the southwest part of the airport) is in DuPage County.

The area is a transportation hub containing O'Hare International Airport as well as major roads such as Interstate 90, its auxiliary Interstate 190, Interstate 294, Illinois Route 72, Illinois Route 171, U.S. Route 12 and U.S. Route 45. This allows the O'Hare neighborhood, combined with the nearby suburb of Rosemont, to work as an edge city.

The Blue Line is a 26.93-mile-long (43.34 km) Chicago "L" line which runs from O'Hare International Airport at the far northwest end of the city, through downtown via the Milwaukee–Dearborn subway and across the West Side to its southwest end in Forest Park, with a total of 33 stations (11 on the Forest Park branch, 9 in the Milwaukee–Dearborn subway and 13 on the O'Hare branch). At about 27 miles, it is the longest line on the Chicago "L" system and second busiest, and one of the longest local subway/elevated lines in the world. It has an average of 72,475 passengers boarding each weekday in 2023.

Chicago's Blue Line and Red Line offer 24-hour service, every day, year-round. This makes Chicago, New York City, and Copenhagen the only three cities in the world to offer local nonstop rail service throughout their city limits 24 hours a day, seven days a week. The Blue Line is the only line in Chicago with more than one station having the exact same name. (The Blue Line has two stations at Harlem Avenue: one in the Kennedy Expressway on the Northwest side and one on the Eisenhower Expressway in Forest Park, Illinois. It also has two stations on Western Avenue: one on the segment between downtown and O'Hare, and one immediately west of downtown.) The Blue Line also has two in-system transfers (both in the Loop), and does not share tracks with any other 'L' line.

Schaumburg (/ˈʃɔːmbɜːrɡ/ SHAWM-burg) is a village in Cook and DuPage counties in the U.S. state of Illinois. At the 2020 census, the population was 78,723, making Schaumburg the most populous incorporated village in the United States. Schaumburg is around 26 miles (42 km) northwest of downtown Chicago and 10 miles (16 km) northwest of O'Hare International Airport. It is part of the Golden Corridor.

Schaumburg's transition from a rural community to a suburban city began with Alfred Campanelli's first large-scale suburban-style development in 1959 and Woodfield Mall's opening in 1971. Schaumburg is bordered by Hoffman Estates and Palatine to the north, Inverness in northwest, Rolling Meadows to the northeast, Elk Grove Village to the southeast, Roselle to the south, Hanover Park to the southwest, and Streamwood to the west.

Interstate 90 (I-90) in the US state of Illinois runs roughly northwest-to-southeast through the northern part of the state. From the Wisconsin state line at South Beloit, it heads south to Rockford before heading east-southeast to the Indiana state line at Chicago. I-90 traverses 124 miles (200 km) through a variety of settings, from farmland west of the Fox River Valley through the medium-density suburbs west of O'Hare International Airport, through Downtown Chicago, and through the heart of the industrial southeast side of Chicago before entering Indiana.

I-90 comprises several named highways. The Interstate runs along the Jane Addams Memorial Tollway (previously called the Northwest Tollway) from South Beloit to O'Hare Airport, the Kennedy Expressway from O'Hare to the Chicago Loop, the Dan Ryan Expressway from the Loop to the Chicago Skyway, and the Skyway to the Indiana state line. The Jane Addams and Chicago Skyway are toll roads maintained by the Illinois State Toll Highway Authority (ISTHA) and the Skyway Concession Company (SCC), respectively. The remainder of the highway is maintained by the Illinois Department of Transportation (IDOT).

United Air Lines Flight 389 was a scheduled flight from LaGuardia Airport, New York City, New York, to O'Hare International Airport, Chicago, Illinois. On August 16, 1965, at approximately 21:21 EST, the Boeing 727 crashed into Lake Michigan 20 miles (17 nmi; 32 km) east of Fort Sheridan, near Lake Forest, while descending from 35,000 feet (11,000 m) mean sea level (MSL). There was no indication of any unusual problem prior to impact. All 30 persons aboard, including six crew members and 24 passengers, were killed.

A definitive cause was not determined by National Transportation Safety Board (NTSB) investigators. However, it was believed that the crash was most likely the result of the pilots misreading their three-pointer (3p) altimeters by 10,000 feet.