Fertility trouble

Politicians tend to talk about Social Security's shortfall as if it is a force of nature like a hurricane or a tornado, something that will happen independent of human choices. In his State of the Union address, for example, President Bush pointed out that 50 years ago, 16 workers paid into Social Security for every retiree who drew benefits. Today, he said, "it's only about three workers and over the next few decades, that number will fall to just two workers per beneficiary."

This is all true, but why is it true? A big part of the answer is that in the 1960s American couples began choosing to have a lot fewer children. The U.S. fertility rate dropped from 3.71 children per woman in the late 1950s to 1.79 in the late 1970s. The fertility rate increased a little during the 1980s and 1990s, but it remains below the "replacement rate" of 2.1. (The replacement rate is higher than 2.0 to account for children who die in infancy.)