WASHINGTON - Children now make up less of America's population than ever before, even with a boost from immigrant families with higher children-to-adult ratios.
Further, when this generation grows up, it will become a shrinking work force that will have to support the expanding U.S. elderly population, even as the government strains to cut spending for health care, pensions and much else.
The latest 2010 census data show that children of immigrants make up one in four people under 18, and are now the fastest-growing segment of the nation's youth, an indication that both legal and illegal immigrants as well as minority births are lifting the nation's population.
Currently, the share of children in the U.S. is 24 percent, below the previous low of 26 percent in 1990. The share is projected to slip further, to 23 percent by 2050, even as the percentage of people 65 and older is expected to jump from 13 percent today to roughly 20 percent by 2050 due to the aging of baby boomers and beyond.
In 1900, the share of children reached as high as 40 percent, compared with a much smaller 4 percent share for seniors 65 and older. The percentage of children in subsequent decades held above 30 percent until 1980, when it fell to 28 percent amid declining birth rates, mostly among white families.
"There are important implications for the future of the U.S. because the increasing costs of providing for an older population may reduce the public resources that go to children," said William P. O'Hare, a senior consultant with the Baltimore-based Annie E. Casey Foundation, a children's advocacy group.
Japan, France, Germany and Canada each has a lower share of children under age 15, ranging between 13 percent in Japan and 17 percent in Canada, while nations in Africa and the Middle East have some of the largest shares, including 50 percent in Niger and 46 percent in Afghanistan, according to figures from the United Nations Population Division.
In the U.S., the share of children under 15 is 20 percent.
Depending on future rates of immigration, the U.S. population is estimated to continue growing through at least 2050. In a hypothetical situation in which all immigration, both legal and illegal, immediately stopped, the U.S. could lose population beginning in 2048, according to the latest census projections.
Since 2000, the increase for children in the U.S., 1.9 million, has been due to racial and ethnic minorities.
Currently, 54 percent of the nation's children are non-Hispanic white, compared to 23 percent Hispanic, 14 percent black, and 4 percent Asian.
During the past decade, the number of non-Hispanic white children declined 10 percent to 39.7 million, while the number of minority children rose 22 percent to 34.5 million. Hispanics, as well as Asians, Native Hawaiians, Pacific Islanders and multiracial children represented all the growth. The number of black and American Indian children declined.
In nearly one of five U.S. counties, minority children already outnumber white children.
The numbers are largely based on an analysis by the Population Reference Bureau, a nonprofit research group in Washington that studies global and U.S. trends. In some cases, the data were supplemented with additional census projections on U.S. growth from 2010-2050 as well as figures compiled by the Annie E. Casey Foundation's Kids Count project.
Nationwide, the number of children has grown by 1.9 million, or 2.6 percent, since 2000. That represents a drop-off from the previous decade, when even higher rates of immigration by Latinos, more likely than some other ethnic groups to have large families, helped increase the number of children by 8.7 million, or 13.7 percent.