Jeff Wheelwright argues that Sun City, Arizona, "the once and future retirement mecca" with a population of 38,000 and a fertility rate of zero, provides a glimpse of our impending demographic troubles:
[Gerontologist Michael Birt] describes a favorite graphic of his, derived from a 2007 United Nations publication. He calls it “Solving for X” because of the problem it raises for the world’s health-care systems. Two lines are crossing, the percentage of people over 65 and the percentage under 5. Back in 1950, children predominated in the world; in 2050 the seniors will be on top. “The percent over 65 and under 5 are trading places,” Birt says. “We’re almost at the X spot.” The forecast date for global X to occur is 2017, but each country will arrive at the transition at a different time. “Japan blasted through its intersection years ago,” he notes.
Was there a single factor to account for this world-shaking reversal? “Yes,” [Jennifer Glick, a sociologist and demographer at the ASU Center for Population Dynamics] says. “You start educating girls.”