According to the Census Bureau, the number of people under 18 fell by 260,000 between 7/1/10 and 7/1/11. The last decline in the child population was in the 70s when the boomers were no longer teens but not yet adults. Before that, it was during the Depression. With the number of births currently depressed by several hundred thousand due to the Great Recession, this population will remain abnormally low for years.