After years of speculation, estimates and projections, the Census Bureau has made it official: White births are no longer a majority in the United States.

Non-Hispanic whites accounted for 49.6 percent of all births in the 12-month period that ended last July, according to Census Bureau data made public on Thursday, while minorities — including Hispanics, blacks, Asians and those of mixed race — reached 50.4 percent, representing a majority for the first time in the country’s history.

Such a turn has been long expected, but no one was certain when the moment would arrive — signaling a milestone for a nation whose government was founded by white Europeans and has wrestled mightily with issues of race, from the days of slavery, through a civil war, bitter civil rights battles and, most recently, highly charged debates over efforts to restrict immigration.

While over all, whites will remain a majority for some time, the fact that a younger generation is being born in which minorities are the majority has broad implications for the country’s economy, its political life and its identity. “This is an important tipping point,” said William H. Frey, the senior demographer at the Brookings Institution, describing the shift as a “transformation from a mostly white baby boomer culture to the more globalized multiethnic country that we are becoming.”

Signs that the country is evolving this way start with the Oval Office, and have swept hundreds of counties in recent years, with 348 in which whites are no longer in the majority. That number doubles when it comes to the toddler population, Mr. Frey said. Whites are no longer the majority in four states and the District of Columbia, and have slipped below half in many major metro areas, including New York, Las Vegas and Memphis.