GEOFF BENNETT: New numbers from the Census Bureau show the U.S. population is older than it's ever been, with the nation's median age now over 38.

William Brangham explains how an older America could pose significant challenges for the economy, work force and social programs in the years to come.

WILLIAM BRANGHAM: Geoff, between 2021 and 2022, nearly every state in the U.S. saw its population's median age go up.

In about a third of states, more than half of the population is older than 40.

Maine had the highest median age of 44.8 years.

And Utah is our youngest state with a median age of 31.9 years.

As the share of older Americans continues to rise, the need for benefits and assistance from Medicare and Social Security will grow.

And, at the same time, an aging work force could cause worker shortages in the years to come.

Joining us to discuss the implications of this shift is Philip Bump.

He is a national columnist for The Washington Post and author of "The Aftermath: The Last Days of the Baby Boom and the Future of Power in America."

Also joining us is Wendy Edelberg.

She's the director of The Hamilton Project at Brookings.

She's a former chief economist for the Congressional Budget Office.

Thank you both so much for being here.

Wendy, to you first.

Geoff mentioned that the median age in the country is 38.

Back in 1980, it was 30.

What is the main reason why this trend line is ticking upwards?

WENDY EDELBERG, Brookings Institution: Well, we have two main effects.

One is that we have improvements in mortality rates.

We are living to older and older ages.

And that is only good news.

But we also, like many countries across the globe, have declining fertility rates.

So we're getting hit on both sides.

WILLIAM BRANGHAM: And, Wendy, do you know why we're having fewer kids in general?

WENDY EDELBERG: This seems to be a trend that goes along with countries as they get richer.

And it isn't, in and of itself, a worrying development.

I mean, it is absolutely true that we are on track for slower labor force growth, about half the pace of growth than in previous decades, recent decades.

But we are also a country that is greatly valued by immigrants.

There are immigrants from all over the world who desperately want to come to the United States.

So we have a very simple way of boosting our population growth, if that becomes a priority for us.

WILLIAM BRANGHAM: Philip, you mentioned both in your book and in your column in The Washington Post that this is not just all Americans getting older.

It's principally white Americans getting older.

Can you explain both that demographic reality and the implications of that?

PHILIP BUMP, The Washington Post: Yes, I mean, I mean, one of the reasons, obviously, also that the United States is getting older is that we had this massive surge in birth from 1946 to 1964 that we call the Baby Boom, right?

This is this massive influx of new Americans all in the same age range.

Now, the size of the Baby Boom has changed over time, both because immigration laws were loosened after the Baby Boom itself and, of course, because people die over time.

But this is also a continuation of the pattern that we saw originating with the Baby Boom, back in the 1940s.

So, you have this big cluster of people all in the same age group that are reaching age milestones together.

And when you think about the year in which there were the most births was 1957, you add 65 to that, the retirement age, and you get 2022.

So we're right at this apex of the Baby Boomers retiring as well.

The Baby Boom was also a very heavily white generation.

Immigration was restricted by law about a century ago, and not lifted until after the Baby Boom was over.

And that led to a very, very white population.

And so what we see when we actually look at the population today is that older Americans are disproportionately white, relative to younger Americans.

The youngest Americans are about half nonwhite.

There are about -- about half of them are Black or Hispanic or Asian.

Older Americans, that's simply not the case.

And so then that, of course, overlaps with a lot of the political and cultural trends that we're seeing in the country.

WILLIAM BRANGHAM: Wendy, there are, as you were touching before, a lot of potential implications here.

One of them, most obviously, it seems that programs like Medicare and Social Security require a larger pool at the bottom to feed the relatively smaller pool at the top.

What does that mean for us policy-wise, if we are seeing this aging population?

WENDY EDELBERG: Payroll taxes, as a share of the whole economy, have been roughly flat for decades and are on track to remain flat over the next decades.

But, at the same time, are spending on Social Security, ignoring the fact that I'm sure we will get into in a second that the trust funds will get exhausted and in -- about in the next decade, Social Security benefits are projected to increase by 50 percent, relative to its share in previous decades, and Medicare, health care spending on the elderly, is projected to double.

So the challenge here is that, largely because of our aging population, but also because of increases in health care costs, we have very significant increases in benefits on the horizon.

But we haven't planned for those with increases in taxes.

WILLIAM BRANGHAM: So, Philip, what -- hearing what Wendy is describing, that demographic reality and the costs going upwards, what are the policy levers policymakers have to try to address that?

PHILIP BUMP: Well, it depends on a number of factors, right?

It depends on the willingness of policymakers to, for example, raise taxes, to increase spending, to potentially reduce the amount of benefits that people are receiving, which, of course, is going to cause a lot of political backlash, should they choose to do so.

It depends on how many people are paying into the system, as was mentioned, if we bring in a bunch of immigrants.

We have seen this strain on the number of people who are being hired.

When I first started researching my book back in 2021, one of the people within my book said, look, we're going to be gasping for jobs, for people to fill these jobs here in short order.

And that came true.

Again, we have seen this pattern over the course of -- from the very beginning.

When the Baby Boom first emerged, we had to build a bunch of schools.

We had to figure out how we were going to do that.

Luckily, we were able to accommodate it.

But one of the changes we're seeing now is the Baby Boom, for really the first time in its existence, is having to compete for power and resources with another comparably sized generation, the millennials.

And so now we see that there's actually additional political tension for the Baby Boom generation at this moment when they have reached a stage that was very much foreseeable, but is causing a lot of strain on the country and the economy.

WILLIAM BRANGHAM: And, Wendy, the tensions that Philip is describing are not easily remedied.

I mean, addressing Medicare and Social Security are third rails of American politics.

Immigration is right behind that.

What do you see as the most likely things that policymakers will do to try to address this?

WENDY EDELBERG: Because of the way that we have organized the Social Security program and the Medicare program, as trust funds, these will become very politically salient over the next several years.

So, because we are spending out more in Social Security benefits and in Medicare benefits, particularly hospital insurance benefits, because we're spending out more than we're taking in, in taxes, the trust fund for Social Security is projected to essentially run out of money by 2031, and the Medicare hospital insurance trust fund soon thereafter.

So what that will mean is that, under current law, if there are no changes, then the Social Security benefits, for example, will be constrained by how many taxes or how big the tax revenues are that are coming in.

And we only take in about 75 percent in taxes for the benefits that go out.

So, without any change in law, you're talking about an across-the-board cut in Social Security benefits of 25 percent.

Talk about third rails.

That will never happen.

And so that will be a strong impetus for policymakers to act.

WILLIAM BRANGHAM: Philip, one of the things that you both have touched on is this -- the idea of bringing in more immigrants to add to that work force, to create more payroll taxes, to help fulfill these gaps.

Again, you cover national politics as closely as anybody.

How likely do you think this issue will help be a lever to true immigration reform in this country?

PHILIP BUMP: To some extent, it depends on what you mean by true immigration reform.

I think it is certainly the case that both parties have a vested interest in changing the system in a way that they might not have previously.

For example, the Republican Party is very heavily old, right?

There are a lot of older Americans who are members of the Republican Party, more so than the Democratic Party.

And that then muffles the longstanding tendency by the Republican Party to say, hey, we need to cut these what they call entitlements, right?

There is no longer the same push within the Republican Party to cut Social Security now that a third of the Republican Party is over the age of 65, right?

So these things are changing.

These things are shifting, and I think it will be the case as well that the Republican Party may be increasingly open to the idea of reforming immigration in a way that makes it sustainable to be able to pay out Social Security benefits, right?

Now the competing instincts that the party has our in tension and need to be resolved.

And so this is a moment of flux.

It is a moment of flux that is caused largely by the Baby Boomers having reached this age.

But it's a moment of flux in which I think the party's positions may themselves change.

WILLIAM BRANGHAM: Such an important, interesting discussion.

Philip Bump, Wendy Edelberg, thank you both so much for being here.

PHILIP BUMP: Thank you.

WENDY EDELBERG: Thank you.