With a wingspan and a nose-to-tail stretch just short of a football field, she is arguably the world’s most recognizable aircraft — a four-engine, humpback testament to American innovation ubiquitous worldwide for nearly five decades.

But the Boeing 747 — the “Queen of the Skies,” the original jumbo, the plane of Air Force One — has become all but obsolete.

“I’ve flown a lot of airplanes. It’s just this thing is iconic, and it’s really easy to fly,” said United Airlines pilot Dean McDavid, the carrier’s director of flight standards and a 19-year 747 pilot, as he stood beside the behemoth at Denver International Airport. “(But) like anything in life, life is about change.”

United, for what’s likely to be the last time, brought a 747 to the Mile High City on Thursday morning on the last leg of a farewell tour across the country for the aircraft — the final chapter in the long history of the carrier and its 747s in Denver. Early next month, the model will fly under United’s banner a final time, ending an era of jumbo-jet travel as domestic carriers phase out the 747 from their fleets by the end of the year.

United, like its U.S. competitors, has moved to more fuel-efficient, twin-engine, wide-body airplanes that can fly just as far but cost much less to operate and maintain. The replacements — from the efficient Boeing 787 Dreamliner and 777 to the Airbus A330 and sleek A350 — also generally have fewer seats, which means they’re easier to sell out.

The 777-300 extended range, for instance, carries about the same number of passengers as the 747-400 (the model United flies) while burning 100,000 pounds less fuel.

“It’s just more economical,” McDavid said.

Even the 747’s distant cousin, the bigger Airbus A380, which can seat more than 500, has become an unpopular purchase option among airlines. As of next year, only international carriers will operate the two aircraft.

But the allure of the 747, and its importance to the nation’s jet age, has made its last trips through the sky emotional, warranting celebrations nearly as large as the aircraft itself. United has given it an elongated and very public farewell for its employees and fans.

Leading up to the November send-off, United has been taking its dwindling — and aging – 747 fleet across the country. The youngest 747 in the airline’s arsenal is 17 years old. The one that came to Denver on Thursday, and which flew hundreds of United workers around the state for a final flight, is 22.

“It’s sad, really, to see it go,” said Denver-based United flight attendant Teri Oates, a 31-year veteran of the airline, as she sat in a business class seat on the jet’s upper floor. “When you see this airplane take off, you just see this bird lift, you can’t even fathom how it can get off the ground. Even after 31 years, I get that feeling.”

United’s last 747 flight is set for Nov. 7, when a jumbo will take passengers on a nostalgia flight from San Francisco to Honolulu featuring homages — from the uniforms, to the food and music — to the airline’s first routes on the airplane in the 1970s. Tickets for the trip sold out in less than two hours.

The last United 747 international flight, from Seoul, South Korea, is scheduled for next week.

Delta Air Lines is set to retire its 747 fleet by the end of this year and is making the sleek Airbus A350 its flagship aircraft. (A Delta A350-900 actually was at DIA last month for high-altitude training.)

American Airlines hasn’t flown a 747 in some 20 years, according to company spokesmen.

International carriers still rely fairly heavily on the 747, with Lufthansa and British Airways still operating once-daily 747-400 flights from DIA to Frankfurt and London’s Heathrow Airport, respectively.

“We regularly review our network and consider a number of commercial and operational factors to ensure that we have the right service to meet our customers’ needs,” a British Airways spokeswoman said when asked how long it would fly the 747 into Denver.

The airline began flying the jumbo into Colorado in 2015, using a Boeing 777 on the route before that.

“We have no plans right now of changing that aircraft on the Frankfurt route,” Tal Muscal, Lufthansa’s spokesman for the Americas, told The Denver Post this week. Lufthansa has been using the 747 in Denver since 2003 and operated an Airbus A340 to Munich.

Lufthansa was the launch customer purchaser of Boeing’s 747-8, the latest version of the 747, which has upgraded engines and is made of lighter materials, but didn’t have spectacular sales. One of Lufthansa’s 747-8s touched down in Denver earlier this year to fanfare.

It also flies a large fleet of Airbus A380s, a true, full double-decker aircraft that is the world’s largest for carrying passengers.

“There is a great demand, and we have to fill it,” Muscal said, explaining that the large planes allow the airlines to ferry more passengers to Asian destinations where they can operate only a limited frequency of flights.

Boeing has had difficulty selling the 747-8 passenger version, though interest remains for the freight design.

Passengers will be able to travel on the 747 out of Denver for at least the near future, but it’s likely to become more difficult unless you fly frequently or seek one out.

For an aircraft with a long history in the Mile High City, United’s final 747 flight marks the end of an era.

The first jumbo landed in the city, a Continental Airlines flight, on Nov. 18, 1970, at Denver’s Stapleton International Airport, according to the Wings Over the Rockies Air & Space Museum. That was just a little more than a year after the first 747 flew on Feb. 9, 1969.

United and other carriers also used the 747 out of Stapleton. Korean Air, starting in May 1997, used the 747 on a three-times-weekly flight to Seoul until October 1999, DIA says.

By 2006, United had stopped regularly using the 747 out of Denver, according to DIA, though there have been a number of special, high-capacity flights. (Oates, the flight attendant, worked one in February.) Some cargo carriers, like Kalitta Air, still use freight versions of the 747 out of Denver.

Over the years, the 747 has left its impact on the Mile High City, from the iconic images of the plane taxiing over the bridge across Interstate 70 at Stapleton International Airport to memories of the plane flying over the city.

“When the 747 was first created, United Airlines — and in fact nobody (else) — had sophisticated enough flight simulators that they could do all the flight training in simulators the way they do now,” said James Simmons, a professor of aviation at Metropolitan State University of Denver.

That meant United would train its pilots at Stapleton with late-night touch-and-gos on the airport’s runways. Simmons said he would go out in the dark to catch a glimpse of the plane.

“It was really something,” he said. “I did that several times way back in the late 1970s. … It’s not the biggest airplane, but it’s the one that captured way more public attention.”

A look at the 747 in Colorado over the years: