Northwest Orient Airlines Flight 706 crashes during takeoff from O'Hare International Airport in Chicago, Illinois, killing all 37 people on board.

Northwest Orient Airlines Flight 706 was a Lockheed L-188 Electra aircraft, registration N137US, which crashed on take-off from Chicago's O'Hare International Airport September 17, 1961. All 37 on board were killed in the accident.

Chicago O'Hare International Airport is the primary international airport serving Chicago, Illinois, United States, located on the city's Northwest Side, approximately 17 miles (27 km) northwest of the Loop business district. The airport is operated by the Chicago Department of Aviation and covering 7,627 acres. O'Hare has non-stop flights to 249 destinations in North America, South America, the Caribbean, Europe, Africa, Asia, the Middle East and the North Atlantic region as of Summer 2024. As of 2024, O'Hare is considered the most connected airport in the United States, and fifth most connected airport in the world. It is also the world's fourth busiest airport and 16th largest airport.

Chicago is the most populous city in the U.S. state of Illinois and in the Midwestern United States. Located on the western shore of Lake Michigan, it is the third-most populous city in the United States with a population of 2.74 million at the 2020 census, while the Chicago metropolitan area has 9.41 million residents and is the third-largest metropolitan area in the nation. Chicago is the seat of Cook County, the second-most populous county in the United States.

Illinois is a state in the Midwestern region of the United States. It borders Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash and Ohio rivers to its south. Of the fifty U.S. states, Illinois has the fifth-largest gross domestic product (GDP), the sixth-largest population, and the 25th-most land area. Its capital city is Springfield in the center of the state, and the state's largest city is Chicago in the northeast.