Fertility

The countries with the highest immigrant populations

Data: Pew Research Center; Chart: Axios Visuals

Robust immigration has buoyed the populations of the U.S., U.K. and other developed nations, keeping them from shrinking for now. But a number of aging countries don't have enough immigration to replace their population as their fertility rates continue to plummet.

The bottom line: The control of borders is a serious political problem, but experts are eyeing legal immigration as one solution to a future demographics challenge. As nations age, many will be short of workers to support social programs relied on by the older population.

The countries with the highest immigrant populations

Data: Pew Research Center; Chart: Axios Visuals

One point that's often lost in heated debate is that immigration could be vital in helping countries to have enough young workers in the economy to support their aging populations.

The bottom line: The control of borders is a serious political problem, but experts are eyeing legal immigration as one solution to a future demographics challenge. As nations age, many will be short of workers to support social programs relied on by the older population.