Affordable housing

Chart: How many people of each age live in U.S. cities

Data: IPUMS-USA, University of Minnesota; Chart: Naema Ahmed/Axios

The global aging trend is leading to millions of empty homes

Vacant homes in New York
Vacant houses in Newburgh, New York. Photo: Don Emmert/AFP/Getty

Japan's aging trend is swelling the number of vacant houses in the country: There were 3.47 million vacant private homes in Japan last year, up 9.1% since 2013. That's 5.5% of the total number of houses, according to Tomohiro Ebuchi and Shohei Nomoto of Nikkei.

The context: That's a lot, but the surge of housing vacancies — for varying reasons — is a global trend.