Deaths now outnumber births among white people in more than half the states in the country, demographers have found, signaling what could be a faster-than-expected transition to a future in which whites are no longer a majority of the American population.

The Census Bureau has projected that whites could drop below 50 percent of the population around 2045, a relatively slow-moving change that has been years in the making. But a new report this week found that whites are dying faster than they are being born now in 26 states, up from 17 just two years earlier, and demographers say that shift might come even sooner.

“It’s happening a lot faster than we thought,” said Rogelio Sáenz, a demographer at the University of Texas at San Antonio and a co-author of the report.