PHOENIX — Non-Hispanic whites will make up less than half the national population by 2050, according to a new study.

And Arizona could reach that rate even sooner.

The report Monday by the Pew Hispanic Center figures that Hispanics nationwide will be 29 percent of the total by the middle of the decade. That is more than double the current figure.

Arizona already is there: The U.S. Census Bureau pegged this state’s Hispanic population in 2006 at 29.4 percent.

In fact, the Census Bureau found in 2006 that the rate of Hispanic growth in Arizona already is faster than the national average: The number of Hispanics in the state went up nearly 6 percent just in one year, versus just 3.4 percent nationwide.

Having non-Hispanic whites as reduced from a majority to a just plurality nationwide by 2050 is based on more than just Hispanics reaching 29 percent of population. It also presumes that black population will remain at close to the current 13 percent of the total and Asian population growing from 5 percent of the total now to 9 percent.

That puts the “majority” Anglo population at just 47 percent.

Jeffrey Passel, senior research analyst at Pew Hispanic, told Capitol Media Services that predicting exactly what year non-Hispanic whites will no longer be 50 percent of the population in Arizona is difficult.

“I suspect a lot will depend not only on international migration but on migration from other states,” he said. “Will the new migrants from other states be overwhelmingly white, or will they include Latinos/blacks/Asians chasing economic opportunities and/or retiring there?” Passel said.

Overall Pew Hispanic estimates that 82 percent of the total increase in national population between now and 2050 will be due to immigrants arriving in this country — legal and otherwise — and their children born as U.S. citizens.

And nearly one in five Americans by 2050 will be immigrants, the study says, compared to just one in eight now.

That number of immigrants, the study suggests, could make a difference in the ability of the country to support a growing elderly population.

According to the Pew study, the nation’s current “dependency ratio” is 59. That is the number of people below the age of 18 or older than 64 compared with 100 people of working age.

By 2050, the report says, that ratio will rise to 72. That is based on 32 people of retirement age per 100 adults of working age, and 40 children.

The Pew study does not have Arizona-specific figures.

But in a 2005 report, the U.S. Census Bureau looked at the aging population here. And its figures show an even more pronounced change.

By 2030 — 20 years before the statistics in the Pew study — the Census Bureau predicts there will be 41 seniors in Arizona for every person of working age and 45 children younger than 18, meaning a dependency ratio of 86.

The Pew study says the nationwide ratio is linked to immigration.

It figures that if the number of people coming to the United States from elsewhere is higher than estimated, the ratio will be lower than predicted, as there will be more people of working age.

Conversely, if immigration slows, then the ratio will go higher as there will be fewer working-age people.