Congress is wrestling with what to do when the inevitable happens.

Sometime in the next two decades, Arlington National Cemetery, the iconic resting place for generations of military veterans, will no longer be able to accommodate new arrivals.

“Unfortunately, the cemetery is rapidly running out of space. If nothing is done, in a matter of 23 short years, the cemetery will be closed for new burials,” said Rep. Mike Coffman, R-Colo., at a House subcommittee hearing this week.

Congress is looking at two options to extend the life of Arlington as an active cemetery: making it harder to get in, or finding more hallowed ground.

More than 400,000 people have been interred at the cemetery in its 153-year history, which dates back to the Civil War.

Today, there are just over 100,000 spaces left. About one-third are below-ground spaces, and the remainder are in columbariums, the niche walls in which urns are stored.

The cemetery does have plans for some limited expansion, but not enough to keep Arlington open much past 2040, given the current rate of burials of more than 7,000 a year.

“Unfortunately, without changes to the eligibility requirements and the physical footprint, Arlington National Cemetery will not be a burial option, for most who served in the Gulf War or any conflicts since, regardless of their contributions, achievements, or valor,” testified Karen Durham-Aguilera, executive director of Army National Military Cemeteries at Thursday’s hearing.

The Army says in order to meet its goal of keeping Arlington an active cemetery for the next 150 years, it needs to tighten the requirements for burial.

“We are very sensitive to the fact that many who have served or are currently serving would be impacted,” Durham-Aguilera said, but said “expansion alone will not keep the cemetery open” to new interments past the 2040s to 2050s.

“We must address the demand for internment by restricting eligibility in addition to physical expansion,” she said.

Many veterans groups oppose any change to the rules that allow most honorably discharged veterans to request burial at Arlington.

“Expansion of the cemetery grounds, contiguously or not, is a viable path forward and is the preferred method of extending the life of the cemetery,” testified Forrest Allen, on behalf of the Military Officers Association of America. “While it is costly and time-consuming, MOAA members have clearly indicated their preference for expansion over significantly restricting eligibility.”

The idea of buying land that’s not physically connected to the current cemetery, perhaps not even in the same jurisdiction, raised concerns that the new burial ground wouldn’t enjoy the same hallowed status as Arlington.

“While such sites might not have the same feel at the outset, there is potential for that aura to develop over time; recall after all, that Arlington Cemetery we know today did not develop its reputation overnight,” Allen said. “Eligibility restrictions,” he added, “are a tougher sell.”

But Gerardo Avila of the American Legion argued that without tighter rules, the current 11 Medal of Honor recipients from Iraq and Afghanistan would likely be denied the option of burial at Arlington, assuming they live to their average life expectancy.

In 2016, the American Legion voted at its national convention to endorse rules that would restrict eligibility to service members who die on active duty, decorated veterans, disabled World War II veterans, retirees, eligible spouses, and children; former prisoners of war; and presidents or former presidents.

Rep. Don Bacon, R-Neb., a retired Air Force brigadier general, said he would gladly give up his spot to a hero who had displayed extraordinary valor.

“If I take the criteria that's being recommended, I won't be allowed to be buried there either,” Bacon said. “But I think I would prefer keeping that spot open for a Medal of Honor winner and someone who paid the ultimate sacrifice.”

But with an estimated 22 million veterans alive today, it's clear that no policy will guarantee them all a spot in Arlington or even the 135 other national cemeteries, or the more than 100 state-run veterans cemeteries in the nation.

“We do believe that we're looking at every possibility and what we can do, but we also know that we cannot serve an entire population, no matter what,” Durham-Aguilera said. “We are filling up every day."

Section 60, where the nation’s most recent war dead are buried, will be closed in the next three to four years, she said.

Congress is expected to make a decision about the future of Arlington National Cemetery this year.