The shuttle buses will soon be relocated to Philadelphia. And the air stairs, no more.

After nearly 25 years, officials at Reagan National Airport on Thursday unveiled a much-anticipated addition, a sleek 14-gate concourse that will mark the end of operations of the much-maligned Gate 35X.

American Airlines will begin service Tuesday out of the new concourse — a prospect that will delight long-suffering travelers. Chief among them, prominent members of Congress, who despite their committee leadership and top-secret clearances, found themselves cooling their heels in the same dim, 4,900-square-foot space before scrambling aboard a shuttle bus to catch their flight.

“Good riddance,” said Rep. Rodney Davis (R-Ill.), a member of the House Transportation and Infrastructure Committee — and frequent Gate 35X user. “I can’t wait.”

Airport officials are billing Tuesday as a “soft opening,” hoping to use the next few months to adjust to the new space before its official opening in July. Some work is still to be completed, as only two of the dozen or so restaurants and shops will open with the new concourse.

But airline and airport officials were eager to begin using the new building as soon as possible.

“It just feels great,” said Paul Malandrino Jr., a vice president at the Metropolitan Washington Airports Authority who also manages Reagan National Airport. “We’re all very excited with the end result.”

The new space is bright and airy, with high ceilings and skylights that provide natural light. Many features — from the six Jeffersonian domes that top the building to the yellow steel columns scattered throughout — mimic those in other parts of the airport.

In some areas, banks of sleek blue chairs, complete with headrests and ottomans, have been placed by windows for those who want to enjoy the expansive views. Architect Louis Lee said that even though he was designing a building, the goal was to make the space feel as open and natural as possible.

There are other amenities, too, including a pet relief area and a nursing room for parents.

Tuesday’s opening will mark a bright spot for an airport that has watched its once-robust operations reduced to a trickle during the coronavirus pandemic. In 2020, 7.6 million passengers flew through National, compared with 23.9 million in 2019.

On Monday, more than 14,000 people went through Transportation Security Administration checkpoints at the airport, the most since the pandemic began. With passenger traffic on the rebound, experts say the timing couldn’t be better for the new concourse.

“This will be a very good thing for the economy,” said Mahmood Khan, a professor and director in the Department of Hospitality and Tourism Management at Virginia Tech’s Arlington campus. “It comes at an opportune time, when businesses are trying to get back on track.”

Elliott L. Ferguson, executive director of Destination D.C., the city’s chief tourism and event promotions organization, said the new concourse will be a welcome addition, benefiting residents and the millions of visitors he hopes soon will return to the city.

The airport’s proximity makes it a popular choice for travelers, Ferguson said. But despite its relatively compact footprint, it has its quirks and can be difficult to navigate. Among the most notable is Gate 35X, which requires passengers to wait upstairs before taking an escalator down to a holding area where they waited to be loaded onto shuttle buses to their flight.

“It was just not a user-friendly option,” Ferguson said.

At its peak, more than 6,000 people flew through Gate 35X each day, with American operating an average of 78 daily departures through the gate. The new concourse will spread those arrivals and departures over the 14 new gates.

It will be a big upgrade for travelers, offering an experience more in keeping with an airport that serves the nation’s capital, Ferguson said.

Reagan National’s 230,000-square-foot addition is the airport’s biggest upgrade in nearly 25 years. Dubbed Project Journey, the $1 billion package of improvements also will move security checkpoints at Terminals B and C into new buildings and increase the number from 20 to 28.

The project is being paid for through the sale of bonds and by fees that passengers pay when purchasing airline tickets.

Airport officials originally had planned to open the security checkpoints ahead of the new concourse, but construction issues have delayed the opening until late summer or early fall.

Once that portion of the project is complete, only ticketed passengers will have access to National Hall — a possible boon for merchants who expect passengers to spend more money because they won’t have to rush through security to their gates. The changes might be a disappointment for the general public, which no longer can enjoy views of the airfield from the glass-enclosed space — or the bowl of chowder from Legal Seafood.

Ultimately, the project will do away with temporary workarounds to move passengers through an airport never built to handle as many people as it does or the additional security requirements in the aftermath of the Sept. 11, 2001, terrorist attacks. Once complete, travelers will be able to move between Terminals B and C without having to board a shuttle bus or make repeat trips through airport security.

Airport officials mindful of noise concerns are quick to say the new concourse is not an expansion but an upgrade that joins into one building the 14 separate spaces where Gate 35X aircraft previously parked.

Whether the new concourse will be enough to lure passengers from Baltimore-Washington International Marshall Airport is not clear, in part because the region’s three major airports have managed to carve out their own niches, said Virginia Tech’s Khan.

BWI is popular among budget-conscious travelers. Washington Dulles International, National’s sister airport, dominates the international market, and National is favored by those seeking quick access to the city.

For their part, BWI officials have invested heavily over the years to maintain their position as the top airport in the region.

Three years ago, BWI completed a $60 million upgrade to its international concourse, adding six gates. Airport officials also recently completed work on a $48 million, 55,000-square-foot extension that added five gates, new concession space and restrooms to Concourse A. Later this year, work also will begin on a three-level expansion that will connect its A and B concourses.

No matter the outcome, officials say, better airports are good for business.

“People come to D.C. with a lot of expectations, particularly those who haven’t been to the capital,” Khan said. “And those first impressions matter.”