WASHINGTON — White people will no longer make up a majority of Americans by 2043, according to new census projections. That’s part of a historic shift that already is reshaping the nation’s schools, workforce and electorate, and is redefining long-held notions of race.

The official projection, released Wednesday by the Census Bureau, now places the tipping point for the white majority a year later than previous estimates, which were made before the impact of the recent economic downturn was fully known.

America continues to grow and become more diverse due to higher birth rates among minorities, particularly for Hispanics who entered the U.S. at the height of the immigration boom in the 1990s and early 2000s. Since the mid-2000 housing bust, however, the arrival of millions of new immigrants from Mexico and other nations has slowed from its once-torrid pace.

The country’s changing demographic mosaic has stark political implications, shown clearly in last month’s election that gave President Barack Obama a second term — in no small part due to his support from 78 percent of non-white voters.

There are social and economic ramifications, as well. Longstanding fights over civil rights and racial equality are going in new directions, promising to reshape race relations and common notions of being a “minority.” White plaintiffs now before the Supreme Court argue that special protections for racial and ethnic minorities dating back to the 1960s may no longer be needed, from affirmative action in college admissions to the Voting Rights Act, designed for states with a history of disenfranchising blacks.

Residential segregation has eased and intermarriage for first- and second-generation Hispanics and Asians is on the rise, blurring racial and ethnic lines and lifting the numbers of people who identify as multiracial. Unpublished 2010 census data show that millions of people shunned standard race categories such as black or white on government forms, opting to write in their own cultural or individual identities.

By 2060, multiracial people are projected to more than triple, from 7.5 million to 26.7 million — rising even faster and rendering notions of race labels increasingly irrelevant, experts say, if lingering stigma over being mixed-race can fully fade.

The non-Hispanic white population, now at 197.8 million, is projected to peak at 200 million in 2024, before entering a steady decline in absolute numbers as the massive baby boomer generation enters its golden years. Four years after that, racial and ethnic minorities will become a majority among adults 18-29 and wield an even greater impact on the “youth vote” in presidential elections, census projects.

“The fast-growing demographic today is now the children of immigrants,” said Marcelo Suarez-Orozco, a global expert on immigration and dean of UCLA’s Graduate School of Education & Information Studies, describing the rate of minority growth in the U.S. as dipping from “overdrive” to “drive.” Even with slowing immigration, Suarez-Orozco says, the “die has been cast” for strong minority growth from births.

As recently as 1960, whites made up 85 percent of the U.S., but that share has steadily dropped after a 1965 overhaul of U.S. immigration laws opened doors to waves of new immigrants from Mexico, Latin America and Asia. By 2000, the percentage of U.S. whites had slid to 69 percent; it now stands at nearly 64 percent.

“Moving forward, the U.S. will become the first major post-industrial society in the world where minorities will be the majority,” Suarez-Orozco said. With the white baby-boomer population now leaving the work force, the big challenge will be educating the new immigrants, he said.

The U.S. has nearly 315 million people today. According to the projections released Wednesday, the U.S. population is projected to cross the 400 million mark in 2051, 12 years later than previously projected. The population will hit 420.3 million a half century from now in 2060.

By then, whites will drop to 43 percent of the U.S. Blacks will make up 14.7 percent, up slightly from today. Hispanics, currently 17 percent of the population, will more than double in absolute number, making up 31 percent, or nearly 1 in 3 residents, according to the projections. Asians are expected to increase from 5 percent of the population to 8 percent.

Among children, the point when minorities become the majority is expected to arrive much sooner, in 2019. Last year, racial and ethnic minorities became a majority among babies under age 1 for the first time in U.S. history.