If “demographics are destiny,” what’s in store for the U.S. economy?

The U.S. population recently reached a demographic milestone with global economic implications: A record 4.18 million people reached retirement age last year.

“Demographics are destiny,” ADP Chief Economist Nela Richardson told “Marketplace” host Kai Ryssdal during a conversation in Cumberland County, Tennessee, where more than a third of the population is 65 years or older. “What Cumberland represents is that tension between an aging population and a workforce who is struggling to keep up.”

That conversation was two years ago. Since then, Ryssdal and Richardson have reported on the connection between age demographics and the economy around the world — they have visited five cities in four countries on three continents for our series, “The Age of Work.”

Having just wrapped up another leg of this reporting in Mumbai, India, Ryssdal and Richardson reflected on some of their takeaways from this project.

The following is an edited transcript of their conversation.

Kai Ryssdal: All right, two long years — literally around the world. What are your big takeaways?

Nela Richardson: Well, I have three. One: Growth is really messy. This is something they don't teach you in econ grad school. Growth is just an equation, but the equation cannot capture how messy real growth is. The second thing I learned was how connected these stories are — and I mean connected on a personal level. We can talk about the global economy. We can talk about trade and the U.S. being Vietnam's primary market for their goods, and India being a primary market for U.S. talent — and a lot of that is already in the discourse. But what occurs to me is how connected our personal stories are. The "I'm going to work till I die" in Cumberland [County], Tennessee, is just as pervasive as in Mumbai, India. But the third thing — I just had a conversation with my 18-year-old that reflects this third learning. He said, "I just want to do something that matters.” And our jobs, you know, we don't want them to define us, but they give us purpose. And so that's another thing that I learned from this.

Ryssdal: Yeah, I like that last one. That resonates with me. One of the things that hit me through this whole thing is how government policies and sort of exogenous factors to actually running a business can affect even the smallest, tiniest businesses halfway around the world. The manufacturing plant we went to in Vietnam, where he couldn't air-condition the whole plant — and this is in Vietnam, mind you — because of tariff policy in the U.S. And Jay Shroff in Mumbai, and his sister Neha, who had to change their shipping routes because of the war in Iran. it folds into even the tiniest, smallest businesses — and they're basically powerless. They’ve just got to kind of ride with it.

Richardson: Yeah, it's almost like the global version of the butterfly effect — but these aren't little vibrations. Let's be honest. These are sweeping changes in how policy has been executed, and they're being felt in a really deep way around the world. This is part of that global connectivity. Whether it's policy, whether it's an extreme climate event, whether it's an amazing new technology that we call AI. All of it connects all of us, and that is the demographics of this workforce. We're all affected by things that are happening around the world, whether we see them or not.

Ryssdal: You know what hits me every time that I tell people about this series. You know, we got back from India, and everybody was like, "How's India?” and this and that. And so I told them about the project and how, in 50 years — less, probably — the economic advantage, if you will, among countries with prime-age workforces who are on the rise is going to be really substantial, and they had no idea, and it hadn't even entered their thought process. And I think probably we're not ready for that, you know?

Richardson: Kai, I think your perception of a slow-moving tidal wave is spot on. It's the fact that age and ageism, you know, it's the longest-moving trend out there. It was almost like it's moving so slow we didn't recognize it. But that doesn't mean that they're not meaningful and shifting the ground underneath our feet. And because we haven't recognized it, we haven't really prepared for it as a global economy, and I think that's what's next. How do you prepare for what is the eventuality of our century — that our demographics are changing and they're affecting not just the economy or our own personal lives?