In 1960, more than a third of the U.S. population was under 18.
During the 1930s and early 1940s, many Americans held off on starting families because of the economic insecurity of the Great Depression and uncertainty of World War II. But the prosperous postwar era led to an increase of births between 1946 and 1964 that gave the baby boomer generation its nickname. Over this 19-year period, the booming birth rate helped the U.S. population grow by more than 50%. The country’s demographic makeup shifted so rapidly that by 1960, there were 64.2 million Americans under age 18, out of 180 million overall — a whopping 36% of the population. For context, in 2022, an estimated 22.4% of the U.S. population was under 18.
General fertility rates in the baby boom era peaked in 1957 at 122.9 live births for every 1,000 women aged 15 to 44 — that’s 4.3 million babies that year alone. The general fertility rate took a nosedive throughout the 1960s as the birth control pill became more widely available and women entered the workforce at much higher rates. By 1970, the general fertility rate was 87.9, and the much smaller Generation X was well underway.
The baby boomer generation didn’t reproduce at the same rapid clip as their parents, but because there were so many of them, they still produced a lot of offspring. Indeed, 1990 — the year all those 1957 babies turned 33 — was another banner year for births, with 4.2 million millennials entering the world, despite a general fertility rate of just 70.9.
