Ethnic and racial minorities will comprise a majority of the nation’s population in a little more than a generation, according to new Census Bureau projections, a transformation that is occurring faster than anticipated just a few years ago.

The census calculates that by 2042, Americans who identify themselves as Hispanic, black, Asian, American Indian, Native Hawaiian and Pacific Islander will together outnumber non-Hispanic whites. Four years ago, officials had projected the shift would come in 2050.

The main reason for the accelerating change is significantly higher birthrates among immigrants. Another factor is the influx of foreigners, rising from about 1.3 million annually today to more than 2 million a year by midcentury, according to projections based on current immigration policies.

“No other country has experienced such rapid racial and ethnic change,” said Mark Mather, a demographer with the Population Reference Bureau, a research organization in Washington.