A version of this story appeared in CNN’s What Matters newsletter. To get it in your inbox, sign up for free here.

CNN —

Jimmy Carter sets a new record on October 1, his birthday, when he will become the first American president to reach triple digits.

It’s a milestone more and more Americans will reach in the years to come – and something the American social safety net is not prepared for.

Carter’s post-presidency began in 1981 after he lost his bid for reelection and when he was 56, too young for Social Security and Medicare.

A very long, incredible retirement

Carter did not dedicate his post-presidential life to sitting on corporate boards and raking in speaking fees, as other recent presidents have done.

Carter got his hands dirty building houses, took on peace missions to Cuba and the Middle East, negotiated the release of hostages, lived in his home town, taught Sunday school and college classes, wrote books, and won Grammys.

His has been, indisputably, the longest, most righteous and most productive post-presidency in history, although John Quincy Adams’ post-presidential, anti-slavery efforts in Congress get honorable mention.

In the nearly 44 years since he left office, Carter helped essentially eradicate Guinea worm, a parasite that infected around 3.5 million people in the mid-’80s and just 14 in 2023, according to The Carter Center.

It’s been 22 years since he won the Nobel Peace Prize in 2002, just as the US was preparing for war in Iraq. Carter also paid a landmark visit to Cuba that year.

It’s been nine years since Carter announced at a news conference that he had been diagnosed with brain cancer and might not have long to live.

CNN’s Stephen Collinson wrote at the time:

“I have had a wonderful life,” Carter said with the same unsparing honesty and meticulous detail that marked his presidency. “I’m ready for anything and I’m looking forward to new adventure,” Carter said, in the 40-minute appearance before the cameras, in which he frequently beamed his huge smile and never fell prey to emotion. “It is in the hands of God, whom I worship.”

Carter had more to do

By December 2015, Carter announced that after treatment, the cancer was gone. A timeline of his life maintained by CNN’s research library has many more notable entries.

It’s been nine years since Carter published an autobiography, “A Full Life: Reflections at Ninety.” He won a Grammy Award – his second – for the audiobook. He would win a third a few years later.

It’s been seven years since he was hospitalized for dehydration in Winnipeg, Canada, where he was outdoors – still working! – for Habitat for Humanity, the organization with which he had a long association.

It’s been five years since 2019, when he won that third Grammy, broke his hip and joked that there should be an age limit on the presidency since he couldn’t have done the job at 80. That was also the year he turned 95 and became the longest-living American president, surpassing George H.W. Bush.

It’s been nearly two years since Carter entered hospice care and nearly one year since his wife, Rosalynn, died. They were married in 1946.

More people will turn 100

As remarkable as Carter made his years since American voters retired him from the White House, there’s also something increasingly normal about people living to 100.

Former presidents, all well-to-do and protected by a generous pension, aren’t a representative sample of society, but it’s notable that the four oldest former presidents – Carter, Bush, Gerald Ford and Ronald Reagan – all lived in the 21st century.

Overall, US life expectancy dropped during the Covid-19 pandemic. It has not yet returned to pre-pandemic levels, and it lags behind other developed countries, according to an analysis by KFF. As of 2022, the life expectancy for US males was 74.8 and for US females was 80.2.

But the population of 100-year-olds is expected to quadruple in the coming decades, according to Pew Research Center. It estimated in January that the current number of centenarians was around 101,000 and that the figure would increase to about 422,000 within 30 years, a small but growing portion of the US population as the average age increases and the birth rate declines.

CNN’s Eva Rothenberg wrote a year ago about the challenges many Americans will face later in life as they live longer, with more than half of older Americans likely needing long-term care in the future – something that many will not be able to afford and that is not covered under Medicare, the federal health insurance program that primarily benefits older Americans.

A major issue during Carter’s presidency and in 1980

Carter signed a law in 1977 that increased taxes to pay for Social Security and changed how benefits were calculated for younger people, which was supposed to help the program’s finances. Later, in 1980, Carter signed additional legislation to control the growth of disability benefits.

In the 1980 presidential election, which Carter ultimately lost to Reagan, the long-term viability of Social Security and Medicare was a major campaign issue and featured prominently in debates. And with good reason: The long-term viability of the social safety net programs, despite the law Carter signed in 1977, was still in serious question.

“There you go again,” Regan said dismissively to Carter in a presidential debate, denying that he opposed the very idea of Medicare. Reagan said he simply opposed the version that became law. Carter later accused Reagan of what we might today call “gaslighting” voters on the issue.

“Governor Reagan has a right to change his mind. He does not have a right to rewrite history,” Carter said in a statement days before Election Day that year.

Reagan, despite his previous opposition to safety net programs, vowed during the campaign to tend to their finances. Carter, on the other hand, was talking about creating a new national health insurance plan, which remains a dream for many Democrats.

More tough changes under Reagan

As president, after first unsuccessfully proposing benefit cuts, Reagan empaneled a commission, chaired by Alan Greenspan, that suggested fixes – some of which ultimately became law in 1983, and not a moment too soon. Social Security was months or weeks away from being able to pay full benefits in 1983, according to the Congressional Research Service.

The 1983 tweaks to Social Security included, for instance, the counting of some Social Security benefits as taxable income and a gradual increase of the retirement age from 65 to 67.

How gradual? The increase is still kicking in more than 40 years later. The 1983 amendments made the full retirement age 67 for people born in 1960 or later. So those seniors still have a few years to go, although people can retire early for a reduced benefit.

That 1983 law, passed near the beginning of Carter’s very early and long political retirement, was the last major structural change to address the solvency of Social Security. There have been more frequent tweaks and major changes to Medicare.

Now the social safety net programs are again teetering on insolvency. Social Security will be unable to pay full benefits in just over a decade, according to the government. Medicare has a smidge more time.

Today, there are new calls to incrementally raise the retirement age or increase the taxes that fund Social Security, which apply only to the first $168,600 of income.

Like in the 1970s and 1980s, changes to the safety net will require a serious debate on all sides of the issue. It’s a debate few people are having at the moment.

Neither presidential candidate this year is talking much about the long-term funding of these programs. In fact, one of Donald Trump’s major proposals is to end the taxation on Social Security benefits that Reagan and lawmakers imposed in 1983. Vice President Kamala Harris has a vague plan to impose new taxes on the wealthy.