For the first time in U.S. history, whites of European ancestry account for less than half of newborn children, marking a demographic tipping point that is already changing the nation's politics, economy and workforce. 
 
 Among the roughly four million children born in the U.S. between July 2010 and July 2011, 50.4% belonged to a racial or ethnic group that in previous generations would have classified them as minorities, up from 48.6% in the same period two years earlier, the Census Bureau said Thursday. That was the first 12-month stretch in which non-Hispanic white children accounted for less than half the country's births. 
 
 The 2008 election of Barack Obama as America's first black president was in some ways emblematic of the nation's changing face. But as the population evolves toward a more-varied mix that includes fast-growing Asian and Hispanic populations, the black/white divide that characterized the civil-rights movement has itself become a relic. 
 
 William H. Frey, a demographer at the Brookings Institution, says African-Americans are the largest minority among adults over 50. But for anyone younger—including the newborns forming America's first "majority minority" generation—Hispanics are the second-largest population group after whites of European descent. 
 
 "It's a major turning point for American society," he said. "We're moving from a largely white and black population to one which is much more diverse and is a big contrast from what most baby boomers grew up with." 
 
 Thursday's census data also show that immigration isn't the main driving force behind America's growing diversity. In fact, the shift has as much to do with the aging white population as the growth in other groups. The total number of births declined between July 2010 and July 2011, compared with the same period two years earlier. But among all ethnic groups, non-Hispanic whites saw births decline just over 10%, more than any other group. 
 
 Overall, the white population is barely above the point where births exceed deaths. Last year 1,025 non-Hispanic white children were born for every 1,000 who died, compared with a ratio of 3,940 births to 1,000 deaths for all other ethnic groups, according to Kenneth Johnson, senior demographer at the University of New Hampshire's Carsey Institute. 
 
 Data for 2010 show Hispanic women give birth to 2.4 babies on average, compared with 1.8 babies for non-Hispanic whites, according to the Pew Hispanic Center. But the rapid growth of the Hispanic population isn't just due to higher birthrates: Minority women also are younger on average, so more of them are in childbearing years. 
 
 The growing diversity has spurred debate—and concerns about issues such as immigration and affirmative action in education. For the economy, the rapidly growing nonwhite population gives America a significant workforce advantage over other developed countries. In Japan and parts of Europe, the total population is shrinking as deaths outnumber births. The U.S. is on track to avoid that fate thanks to a higher birthrate as well as immigration. 
 
 Few places illustrate this better than America's heartland, where many rural areas are locked in a cycle of "natural decrease," which happens when more people die than are born. But in pockets of Kansas, Iowa and Nebraska, Hispanics are reviving small towns that would otherwise be in decline. 
 
 Enlarge Image Close Sandy Huffaker for The Wall Street Journal Between July 2010 and July 2011, minorities accounted for 50.4% of births in the U.S. 
 
 In Nebraska, the Latino population jumped 77% between 2000 and 2010, when the state's population overall grew 7%. In 1990, 11.5% of the population under the age of 5 consisted of minorities. In the '90s, most of the growth in the Hispanic population was due to in-migration, but today births are the driving force, said David Drozd, research coordinator at the Center for Public Affairs Research at the University of Nebraska in Omaha. In-migration refers to people moving into a place from other countries and states, rather than people born to those already there. 
 
 Schuyler, Neb., a rural town of 6,211 settled by Irish and German immigrants, is now 65% Hispanic, up from 41% in 2000 and just 4% in 1990. Many Hispanics work at the local meatpacking plant, the largest employer. Others run mom-and-popshops or restaurants on downtown's B Street, where storefronts had stood vacant for years. On a recent spring day, mothers pushing strollers were ubiquitous, said city administrator Mary Peschel, whose office faces the street. 
 
 Not far from Schuyler, at Columbus Community Hospital, between half and 60% of the babies born in the past two years were Hispanic, according to head nurse Diane Ward. "Twenty years ago, a Hispanic baby was rare. Now it's the norm," she said. The hospital has interpreters around the clock, Ms. Ward said, but demand has eased as more Mexican and Guatemalan immigrants learn English. 
 
 The school district has grown 1,800 students from 1,300 in the last decade, largely because of the Hispanic influx. About 90% of the students in the building that houses kindergarten to third graders are Hispanic, said Superintendent Robin Stevens, and six of every 10 students in Schuyler's public high school are Hispanic. 
 
 Before November's balloting, county officials have hired a Spanish-speaking election coordinator and recruited Spanish-speaking poll workers for precincts with large Latino populations. 
 
 Write to Conor Dougherty at conor.dougherty@wsj.com and Miriam Jordan at miriam.jordan@wsj.com ||||| Venus Perez, 3, stands in line with her mother Criseira Perez as she waits to check in for an appointment May 16 at Mary's Center in Washington.A new census report shows a drop in white (non-Hispanic) births to below 50 percent. (Nikki Kahn/THE WASHINGTON POST) 
 
 For the first time in U.S. history, most of the nation’s babies are members of minority groups, according to new census figures that signal the dawn of an era in which whites no longer will be in the majority. 
 
 Population estimates show that 50.4 percent of children younger than 1 last year were Hispanic, black, Asian American or in other minority groups. That’s almost a full percentage point higher than the 49.5 percent of minority babies counted when the decennial census was taken in April 2010. Census Bureau demographers said the tipping point came three months later, in July. 
 
 The latest estimates, which gauge changes since the last census, are a reflection of an immigration wave that began four decades ago. The transformation of the country’s racial and ethnic makeup has gathered steam as the white population grows collectively older, especially compared with Hispanics. 
 
 The census has forecast that non-Hispanic whites will be outnumbered in the United States by 2042, and social scientists consider that current status among infants a harbinger of the change. 
 
 “This is a watershed moment,” said Andrew Cherlin, a sociologist at Johns Hopkins University who specializes in family issues. “It shows us how multicultural we’ve become.” 
 
 Although minorities make up about 37 percent of the U.S. population, the District and four states are majority minority — California, Hawaii, New Mexico and Texas. 
 
 Metropolitan Washington, where whites are in the minority, is far ahead of the curve. Among children younger than 5, there are more minorities than whites in virtually every jurisdiction except Arlington and Loudoun counties. Statewide, Virginia has just barely more white children under age 1 than minorities, but they are on the verge of falling below half. 
 
 One of the biggest factors in the demographic change is age. Whites are by far the oldest group. Their median age is over 42, so many are beyond their prime childbearing years. In contrast, the median age for Hispanics is under 28. Blacks and Asians have median ages in their early 30s. 
 
 As the number of white women in their 20s and 30s declined over the past decade, the number of white children dropped in most states, said Kenneth Johnson, a sociologist with the University of New Hampshire. 
 
 “The population is literally changing before us, with the youngest replacing the oldest,” he said. “This is the first tipping point. The kids are in the vanguard of the change that’s coming.” 
 
 Places that serve Hispanic mothers and children are experiencing a baby boom. Mary’s Center, which started in Adams Morgan in 1988 to provide immigrant women with prenatal care, opened its fifth center Wednesday in Adelphi. 
 
 “The people who migrate are the young and healthy people,” said Maria Gomez, founder of the center. “They are fertile, and that’s the cycle of life.” 
 
 Dozens of women who are pregnant or pushing strollers streamed into Mary’s Center on Georgia Avenue on Wednesday to see doctors or social workers. Fourteen toddlers listened to stories narrated in English and Spanish while their parents attended English lessons. 
 
 “There are a lot of kids now, and many of them are Latinos,” said Mayra Jacinto, a native of Guatemala who arrived two hours before her doctor’s appointment, holding her 5-month-old daughter, Ivonne. 
 
 In the short term, it’s not clear whether the baby boom will continue. Immigration from Mexico, the country of origin for the vast majority of Hispanic immigrants in the United States, has come to a standstill and may be moving in reverse. 
 
 William Frey, a demographer with the Brookings Institution, said the slowdown in immigration may delay the nation’s transformation to a majority-minority society from 2042 to 2050 or beyond. But he said it will not prevent it. 
 
 “Eventually, when the economy returns, we’re going to get more immigrants, maybe not from Mexico but from other parts of the world,” he said. Without so many youthful immigrants, he added, the United States would look more like Japan, with its disproportionate share of elderly citizens. 
 
 “We were already seeing a declining youth population in large parts of the country,” Frey said. “Without immigrants, we’d be essentially youthless. We had a perfect storm. We got them all coming, younger immigrants having children, at a time when we really needed them.” 
 
 The future is here, in Northern Virginia, where several hundred thousand immigrants have settled over the past 25 years from societies as different as Vietnam, El Salvador, Ethiopia and Iraq. 
 
 The backgrounds of children enrolled in Head Start programs in the area have changed with each wave of immigrants. From 2010 to 2011, Hispanics held steady, but the number of children of Asian and African origin jumped more than 30 percent, while those with roots elsewhere, such as from the Middle East, doubled. 
 
 “The face of Head Start here has changed, but not the earnest desire of these families to see their children do the best they can,” said Melinda Langford, the Arlington Head Start director for Northern Virginia Family Service, a private nonprofit agency that serves 2,400 children younger than 11. 
 
 At Langford’s program, six in 10 preschoolers have parents who were born in another country. Colorful drawings line the halls and classroom walls, signed with names such as Francisco, Dayana, Khadija, Ureal, Lavand, Betel, Estefany, Brittany and Seid. 
 
 Program officials describe their mission as an affirmation of diversity as well as an educational boost for struggling kids. Sometimes they face cultural challenges, such as parents accustomed to disciplining their children more harshly than U.S. laws allow. To help with communication, Head Start employs class assistants and family advocates who are native speakers of a wide range of languages. 
 
 Cherlin said the immigrant baby boom will eventually taper off. Studies suggest that the children and grandchildren of the newest immigrants will have birthrates much closer to those of non-Hispanic whites. 
 
 “The changes to the country may not be as huge as some people think,” he said. “Immigrants will change our society, but our society will change the immigrants.” 
 
 The new census estimates also offered a glimpse of a region that reflects national trends and in some cases defies them. 
 
 The District continued its rebound, attracting 16,000 new residents from all age groups — in one year gaining almost as many people as the 20,000 it added the entire previous decade. Although the number of African Americans rose by more than 2,000, their proportion dipped below 50 percent for the first time in decades. Whites had the biggest increase, at 8,000. But among babies, the number of Hispanic infants rose the most as a percentage, up 70 percent, to 1,700. The number of infants who are white also rose sharply, while there were fewer African American babies. 
 
 In both Maryland and Virginia, the numbers of Hispanics and Asians continued to grow sharply. The number of blacks increased modestly, while the number of whites was virtually unchanged. 
 
 In Prince George’s County, one of the most affluent majority-black counties in the nation, the number of African Americans declined slightly, while Hispanics and whites gained. 
 
 Staff writers Pamela Constable and Luz Lazo contributed to this report.
– For the first time in US history, a majority of babies are members of minority ethnic groups, according to new census figures. Of the roughly 4 million born between July 2010 and July 2011, 50.4% belonged to minority groups. The data show that the huge demographic shift under way has as much to do with the aging of the white population as it does with the growth in other groups, the Wall Street Journal notes. Births among the non-Hispanic white population dropped a full 10% in that 12-month period. Demographers say that without the growth in the Hispanic population—now America's second-largest population group—there would be a declining population and a disproportionate number of elderly citizens, as in Japan and parts of Europe. "We were already seeing a declining youth population in large parts of the country," a demographer with the Brookings Institution tells the Washington Post. "Without immigrants, we’d be essentially youthless. We had a perfect storm. We got them all coming, younger immigrants having children, at a time when we really needed them."