We currently face one of the most pivotal decisions in O’Hare International Airport’s history: Plan and expand for the future of air travel growth and maintain the Chicago airport’s world-class status, or plague passengers with flight and transfer delays, inefficiency and overcrowding.

Under the original O’Hare Terminal Area Plan agreement, signed by the city of Chicago and the airlines in 2018, O’Hare would gain 25% gate capacity across an improved Terminal 2, to be renamed the Global Terminal, and two satellite terminals. The Global Terminal would be the first of its kind to combine domestic and international gates, and it would double the space of Terminal 2 to become one of the largest, state-of-the-art airport facilities in the United States.

But the increase in gate capacity would overwhelmingly come from the two satellite terminals. They would provide new, spacious concourses with passenger amenities and gates that could accommodate a variety of aircraft. Both components of the project are essential to preserve or elevate O’Hare’s status as the fourth-busiest airport in the world.

However, if United and American airlines had it their way, they would delay the satellite terminals and build only the part of the project that benefits them and doesn’t increase competition. This means putting off the construction of both satellite terminals to focus on the Global Terminal. For a price tag still in the billions of dollars, O’Hare would gain two new gates in 10 years.

The Federal Aviation Administration estimates that enplanements — the total number of passengers boarding aircraft, including transfers — at O’Hare will grow from 32.6 million in 2022 to 71.9 million by 2050.  Adding gates incrementally would set O’Hare behind, with the airports that share the top spots with O’Hare — Hartsfield-Jackson Atlanta, Dallas Fort Worth and Denver International — all planning major upgrades and expansions in the coming years.

In Dallas, they’re expanding three terminals to gain 24 new gates. Atlanta is expanding one of its concourses to provide more space and better amenities and gates that can accommodate larger aircraft.  And since 2020, Denver has added nearly 40 new gates and more commercial space and is now planning for its most ambitious expansion — adding 100 new gates over the next 20 years.

If we don’t meet the moment by also modernizing and expanding O’Hare on a forward-thinking scale — a scale that the airlines signed off on in 2018 — the airport will lose pace. That’s a guarantee.

In the last decade, the city of Chicago and air carriers, with critical federal support, made a $6 billion runway investment to prioritize safety and efficiency at O’Hare in the 21st century. And I strongly supported this smart expansion. Even then, it was a battle to get it accomplished. It took 16 years and faced plenty of critics along the way, including — for a while — the same airlines raising concerns today. But we made it through. Following critical federal support under the leadership of then-Secretary of Transportation Ray LaHood, the runway work was completed in 2021. The project greatly reduced delays and improved efficiency — and O’Hare is better for it.

The natural next step is to capitalize on that previous investment by adding that same capacity in both terminal space and gates. However, the airlines would choose to follow it up with a terminal investment disaster — one that guarantees O’Hare passengers would spend hours in the penalty box waiting for a gate.

The choice is clear: Completion of this project, including the 25% increase in gate capacity promised by the original agreement, is essential not only for Chicago, but also for Illinois, the region and the national aviation system.

U.S. Sen. Dick Durbin is a Democrat from Illinois.