Since its first flight in 1969, the giant yet graceful 747 has served as a cargo plane, a commercial aircraft capable of carrying nearly 500 passengers, a transport for NASA's space shuttles, and the Air Force One presidential aircraft. It revolutionised travel, connecting international cities that had never before had direct routes and helping democratise passenger flight.

But over about the past 15 years, Boeing and its European rival Airbus have introduced more profitable and fuel efficient wide-body planes, with only two engines to maintain instead of the 747's four. The final plane is the 1574th built by Boeing in the Puget Sound region of Washington state.

Thousands of workers on Tuesday joined Boeing and other industry executives from around the world - as well as actor and pilot John Travolta, who has flown 747s - for a ceremony in the company's massive factory north of Seattle, marking the delivery of the last one to cargo carrier Atlas Air.

"If you love this business, you've been dreading this moment," said longtime aviation analyst Richard Aboulafia.

"Nobody wants a four-engine airliner anymore, but that doesn't erase the tremendous contribution the aircraft made to the development of the industry or its remarkable legacy."

Boeing set out to build the 747 after losing a contract for a huge military transport, the C-5A. The idea was to take advantage of the new engines developed for the transport - high-bypass turbofan engines, which burned less fuel by passing air around the engine core, enabling a farther flight range - and to use them for a newly imagined civilian aircraft.

It took more than 50,000 Boeing workers less than 16 months to churn out the first 747, a Herculean effort that earned them the nickname The Incredibles. The jumbo jet's production required the construction of a massive factory in Everett, north of Seattle - the world's largest building by volume. The factory wasn't even completed when the first planes were finished.

Among those in attendance was Desi Evans, 92, who joined Boeing at its factory in Renton, south of Seattle, in 1957 and went on to spend 38 years at the company before retiring. One day in 1967, his boss told him he'd be joining the 747 program in Everett - the next morning.

"They told me, 'Wear rubber boots, a hard hat and dress warm, because it's a sea of mud,'" Evans recalled.

"And it was. They were getting ready for the erection of the factory."

He was assigned as a supervisor to help figure out how the interior of the passenger cabin would be installed and later oversaw crews that worked on sealing and painting the planes.

"When that very first 747 rolled out, it was an incredible time," he said as he stood before the last plane, parked outside the factory.

"You felt elated, like you're making history. You're part of something big, and it's still big, even if this is the last one."

The plane's fuselage was 68.5 metres long and the tail stood as tall as a six-storey building. The plane's design included a second deck extending from the cockpit back over the first third of the plane, giving it a distinctive hump and inspiring a nickname, the Whale. More romantically, the 747 became known as the Queen of the Skies.

Some airlines turned the second deck into a first-class cocktail lounge, while even the lower deck sometimes featured lounges or even a piano bar. One decommissioned 747, originally built for Singapore Airlines in 1976, has been converted into a 33-room hotel near the airport in Stockholm.

"It was the first big carrier, the first wide-body, so it set a new standard for airlines to figure out what to do with it, and how to fill it," said Guillaume de Syon, a history professor at Pennsylvania's Albright College who specialises in aviation and mobility.

"It became the essence of mass air travel: You couldn't fill it with people paying full price, so you need to lower prices to get people onboard. It contributed to what happened in the late 1970s with the deregulation of air travel."

The first 747 entered service in 1970 on Pan Am's New York-London route, and its timing was terrible, Aboulafia said. It debuted shortly before the oil crisis of 1973, amid a recession that saw Boeing's employment fall from 100,800 employees in 1967 to a low of 38,690 in April 1971.

The "Boeing bust" was infamously marked by a billboard near the Seattle-Tacoma International Airport that read, "Will the last person leaving SEATTLE - Turn out the lights."

An updated model - the 747-400 series - arrived in the late 1980s and had much better timing, coinciding with the Asian economic boom of the early 1990s, Aboulafia said. He recalled taking a Cathay Pacific 747 from Los Angeles to Hong Kong as a twentysomething backpacker in 1991.

"Even people like me could go see Asia," Aboulafia said. "

Before, you had to stop for fuel in Alaska or Hawaii and it cost a lot more. This was a straight shot and reasonably priced."

Delta was the last US airline to use the 747 for passenger flights, which ended in 2017 - although some other international carriers continue to fly it, including the German airline Lufthansa.

Lufthansa CEO Carsten Spohr recalled travelling in a 747 as a young exchange student and said that when he realised he'd be travelling to the West Coast of the US for Tuesday's event, there was only one way to go: riding first-class in the nose of a Lufthansa 747 from Frankfurt to San Francisco. He promised the crowd Lufthansa would keep flying the 747 for many years to come.

"We just love the airplane," he said.

Atlas Air ordered four 747-8 freighters early last year, with the final one - emblazoned with an image of Joe Sutter, the engineer who oversaw the 747's original design team - delivered on Tuesday.

Atlas CEO John Dietrich called the 747 the greatest air freighter, thanks in part to its unique capacity to load through the nose cone.

Australian Associated Press