My new favorite phenomenon

The donut phenomenon
This article about the demolition of a school in Osaka had an interesting explanation:

At its peak in 1958, the school had 1,270 enrolled students.

But 30 years down the track, the so-called donut phenomenon” had taken hold.

Osaka’s downtown population headed for the suburbs leaving a gaping hole in the city center-and a serious shortage of school-age kids. By 1989, Aijitsu Elementary School had just 47 students and it was forced to integrate the following year with nearby Kaihei Elementary School.

Mmm, donut phenomenon.