Eastern Airlines was a major U.S. domestic airline from 1926 to 1991. It was considered to be one of the four largest carriers during the mid-twentieth century, the other three being American, TWA, and United. Eastern Airlines dominated the air travel market between New York and Florida from the 1930s through the 1950s.

The airline's formation came from the merging of several corporations, notably Pitcairn Aviation and Florida Airways. Pitcairn Flying School and Passenger Service was formed on November 2, 1924, by aviation inventor Harold Pitcairn (1897-1960). Florida Airways was an air mail carrier founded in 1923 by Eddie Rickenbacker (1890-1973), a World War I fighter pilot. On June 1, 1926, Florida Airways started regularly scheduled passenger service. The company revenue from passenger sales was too low, however, and by June 1927, Florida Airways ceased operations. On September 15, 1927, Pitcairn Aviation, Inc. was formed after Harold Pitcairn took over Florida Airways' airmail contract.

In June 1929, Clement Keys (1876-1952), former financial editor of the Wall Street Journal, decided to purchase Pitcairn Aviation, Inc. Keys then resold Pitcairn to North American Aviation, then a holding company for several airline and aircraft companies of which Key was one of the key shareholders. On January 17, 1930, Pitcairn's name changed to Eastern Air Transport, Inc., and soon thereafter the airline expanded its routes to include more cities along the East Coast. In 1934, General Motors purchased Eastern Air Transport, Inc. and changed the name to Eastern Air Lines.

In 1938, Eddie Rickenbacker bought Eastern Air Line from General Motors. Rickenbacker was responsible for setting up Eastern's Great Silver Fleet, a famous fleet of DC-2 aircraft that operated on the East Coast. During this time--from the late 1930s through the 1940s--Eastern enjoyed increasing profits yearly. However, in the late 1950s, Eastern's financial position declined as rival companies began to dominate the market. In 1959, Malcolm A. MacIntyre (1908-1992), a lawyer with no prior experience with airlines, took over as CEO. MacIntyre remained CEO until 1962. Rickenbaker remained as chair of the board until his retirement in 1963.

Floyd D. Hall (1916-2012), businessperson and pilot, served as chair and CEO from 1964 to 1976. Frank Borman (1928-), U.S. Air Force colonel and NASA astronaut, served as chair and CEO from 1975 to 1986. Under his leadership, Eastern profited, but it also suffered due to deregulation and took on new debt for purchasing aircraft, leading to pay cuts, layoffs, and union conflicts. Borman attempted to negotiate with the unions but was unsuccessful.

In 1986, Eastern's board decided to sell the airline to the holding company Texas Air Corporation, whose chair was Frank Lorenzo (1940-), a businessperson with a reputation for cost-cutting and union busting.

The Federal Aviation Administration (FAA) imposed heavy fines against Eastern for major safety violations in 1987. Throughout 1988 and 1990, employees experienced layoffs and severe wage and benefit cuts. The labor unions went on strike and organized walkouts. Relations between the unions and Lorenzo were contentious; the two sides were unable to reach contract agreements.

Eastern Airlines filed for bankruptcy on March 9, 1989. Eastern continued operating until 1990, when it was removed from Texas Air's control, and airline executive Martin Shugrue (1940-1999) was appointed trustee to oversee operations. Shugrue tried to revitalize Eastern but could not do so. The airline ceased operations on January 19, 1991, and assets were liquidated.