Airlines bid farewell to the Boeing 747—Take a look at the life of the 'Queen of the Skies'

A chapter of aviation history is closing this year, as commercial U.S. airlines bid farewell to the Boeing 747, the jumbo jet that made air travel affordable for millions of people around the globe because it could fit hundreds of passengers inside.

The double-decker plane with the humped fuselage is one of the world's most recognizable planes. But after flying the four-engine, fuel-guzzling plane for decades, Delta Air Lines and United Airlines are retiring the so-called Queen of the Skies in favor of sleeker, more fuel-efficient models that are cheaper to operate. The planes are used frequently for cargo, which was part of the inspiration for the plane's design: Some models were given a hinged nose to allow for easy loading of goods.

In a sign of how efficient modern planes have become, Southwest Airlines last month announced it will offer service to Hawaii, and new, single-aisle Boeing 737s will likely do the job.

Delta Air Lines marked the retirement of its Boeing 747s this week with a six-city tour, the last U.S. airline to retire the jumbo jet.

United pulled out all the stops for a farewell flight last month. Its first 747 took off from San Francisco and flew to Honolulu in 1970. It retraced that route for the final passenger flight Tuesday, complete with a crew dressed in 1970s uniforms. Smoking was not permitted, however.

The plane will live on as a workhorse cargo jet, flown by UPS and others.

Here's a look at the Boeing 747, and how it changed the world from its introduction nearly five decades ago:

Joe Sutter, who died last year, led the engineering team that designed the Boeing 747 in the mid-1960s. It took 50,000 employees to bring the plane to life. Boeing says it took 29 months from "conception to rollout," which earned the team the nickname "The Incredibles." Below is a prototype of the jumbo jet in 1968.

The 747's first flight was in February 1969. It entered into commercial service in 1970. The plane was more than 231 feet long and its tail was taller than a six-story building.

Now defunct Pan Am operated the first commercial 747 flight, in January 1970 from New York to London.

Orders rolled in quickly from airlines, including PanAm and TWA. The airlines were eager for the glamour buy and to fill the large planes with thousands of members of the new jet set. Below, airplane tails in 1970.

This mockup shows a configuration of a Boeing 747 that would make any coach-class veteran drool.

Air travel, even in the 1970s, was a luxury, and service aboard the 747 in the early days was elaborate compared with the no-frills era of modern air travel.

Decades before Gulf carriers introduced their flashy cabins, posh lounges were the place to be and be seen in the 1970s. Frank Sinatra Jr. once performed in an American Airlines 747 lounge (with a piano) on a red-eye flight from Los Angeles to New York, an attempt to draw more passengers. The planes could fit some 500 people, and later, airlines got rid of the spacious upper-deck lounges and focused on fitting as many passengers as possible into the plane, which made travel more affordable but less comfortable.

NASA used modified Boeing 747s from 1974 for activities including the study of air turbulence from large aircraft to the more glamorous job of ferrying space shuttles like the Columbia.

The hinged nose of the 747 cargo version allows for easy access to its cavernous interiors.

Cargo is keeping the Boeing 747 alive, even if airlines are turning their backs on the aircraft. UPS last year ordered 14 747-8 freighters, and a surge in e-commerce and air freight could keep them full in the future.

Two Boeing 747-200Bs make up the Air Force One fleet. President Donald Trump late last year complained about the cost of the scheduled replacement of the jets, famously tweeting "Cancel order!"

Delta is retiring its Boeing 747 fleet this year, replacing the jumbo jets with the twin-engine Airbus A350 planes.

British Airways recently announced that it will retire its 747 fleet by 2024.

As the plane becomes a rarer sight at airports, passengers still often stop to get a look at the "Queen of the Skies."