As United Airlines prepares to bring on the Boeing 777-300ER and retire the 747 from its fleet, we take a look back at the connection between these two companies that goes all the way back to the very beginning of commercial aviation. These are two companies who've been partners in flight for nearly 90 years.

United and Boeing were originally part of one company. The carrier’s predecessor company, Boeing Air Transport, was founded on June 30, 1927, as an airline to operate mail routes.

On October 30, 1928, the Boeing Airplane and Transport Corporation was created to handle both airline and aircraft manufacturing operations. The company’s name was changed on February 1, 1929, to United Aircraft and Transportation Corp., which included Boeing Aircraft of Canada, Northrop Aircraft Corp., Stearman Aircraft Co., Sikorsky Aviation Corp. and Pratt & Whitney Aircraft Co.

In March 1931, Boeing Air Transport, National Air Transport, Varney Airlines and Pacific Air Transport combined to form United Air Lines, which offered passenger and mail service from coast to coast. But after an air mail scandal, Congress passed legislation barring aircraft manufacturers from owning airlines. As a result, United Aircraft and Transport Corporation split into its three parts – Boeing, United Aircraft and United Air Lines.

In 1933, United started flying the Boeing 247, a twin turboprop aircraft with technological advances including all-metal construction and one of the first retractable landing gear systems. The aircraft was also able to fly across the country without passengers having to change planes or stop overnight.

By 1947, United’s fleet continued to evolve, first with the Douglas DC-4, and then with the DC-6, which introduced pressurized cabin service for passengers. The DC-6 could also fly coast to coast, only stopping in Lincoln, Nebraska. In the next decade, United’s fleet included DC-6s, DC-7s and Convair CV-240 aircraft.

Meanwhile, Boeing began moving into the jet age in 1952, when it started building the Model 367-80, a four-engine jet that eventually became the 707.

United ended up buying the Douglas DC-8 instead of the 707. It also bought the Caravelle, a shorter-range twinjet made by France’s Sud Aviation, and became the first airline to fly Boeing’s four-engine, shorter-haul 720 jet.

After merging with Capital Airlines in June 1961, United’s fleet underwent more changes, with the addition of the British-built Vickers Viscount mainline turboprop aircraft.

A year later, Boeing rolled out the three-engine 727-100 jet, and United began flying the aircraft in 1964. In April 1965, United placed an order for 66 aircraft and options on another 39 with Boeing, making it the largest commercial order ever made by an airline at the time.

In the same year, Boeing launched the now iconic twin-engine 737. A year after launching the 737, Boeing announced plans to build the nearly 500-seat 747, dubbed the Queen of the Skies. United received its first 747 in August 1970.

In 1978, Boeing began production on both the narrow-body 757 and the wide-body 767. United Airlines was the launch customer for the 767 and it entered the fleet in 1982. Three years later, United bought Pan Am’s Pacific Division for $750 million, which included a fleet of Boeing 747SP and Lockheed L-1011-500 wide-body jets.

On October 29, 1990, Boeing formally moved forward with the 777, with an initial order of 34 airplanes and 34 options by United Airlines. The first 777 was delivered to United on May 17, 1995, and the first flight was from Washington, D.C. to London.

A month later, Boeing’s board authorized production of the Boeing 777-300, and on February 24, 2003, the 777-300ER completed its first flight.

In 2005, the company launched the Boeing 787-8 Dreamliner and delivered its last 757. On July 8, 2007, the first 787 Dreamliner was rolled out at a celebration attended by 15,000 people at Boeing’s Everett, Washington final assembly factory. In 2009, United announced an order of 50 787 Dreamliners, making it the North American launch customer.

Two years after United and Continental Airlines merged in 2010, the airline took delivery of its first Dreamliner to use on international routes to Africa, Asia and Europe. In April 2015, United ordered 10 Boeing 777-300ERs and unveiled the aircraft type in February 2017 – complete with the new Polaris international business class cabin –to fly between San Francisco and Hong Kong.

The future looks bright for the continued partnership between United and Boeing, with more deliveries scheduled for the 777-300ER, the 737MAX and the 787 Dreamliner. These jets will fuel United’s future growth and ensure that passengers can get to the places they want to go.