The birth rate in South Korea, where I live and work, hit a record low this year, leading to concern about the impact an aging (and, eventually, shrinking) population might have on the nation’s society and economy.

These charts show the long-term trends, both in actual population and projected changes, according to United Nations data. I’ve added North Korea, which actually has a higher fertility rate today, for context.

First, let’s look at the populations of the two countries, which share an ethnic background and a (mostly) common language — despite the Korean War-era division of the peninsula.

South Korea has about 51 million residents, roughly twice the number of people in the North, which has 25 million. That’s the number of South Koreans who love in the Seoul metro area, by the way.

Both populations are expected to peak in two decades — and then begin to decline.

That downward trend, for now, is much more pronounced in South Korea because of the nation’s low birth rate. Having a large family in South Korea, where housing and education costs are pricey, isn’t possible or practical for many people. The nation also has relatively weak maternity leave policies (and stubbornly traditional gender roles in the home and workplace), leading women to postpone childbirth to pursue their careers.

South Korea is slightly smaller geographically (about the size of Indiana, in terms of area) than the North (roughly the area of Pennsylvania). So their respective population densities vary, too:

Here’s how South Korea has grown, in five-year-increments, since 1950 — when the Korean War began and ultimately changed the trajectories for both countries. South Korea saw relatively rapid growth rate immediately after the war, perhaps as refugees resettled. Projections show that rate declining by 2035:

The North experienced a rapid decline during the war, mostly likely from the death toll during the conflict, the political purges that followed — and the southern migration before the border was secured. Its growth rate soon recovered, however, but could begin declining again by 2045.

Here’s hoping the Korean fertility rate rebounds, or the two nation’s unify — or either becomes more welcoming and accommodating of immigrants. At things stand now, South Korea could become “extinct” by 2750 — a worrying (though simplistic and imperfect) simulation for a uniquely homogenous society that traces its roots back thousands of years.