FLAGSTAFF, Ariz. — Almost half of American Indians and Alaska Natives identify with multiple races, representing a group that grew by 39 percent over a decade, according to Census data released Wednesday.

Of the 5.2 million people counted as Natives in 2010, nearly 2.3 million reported being Native in combination with one or more of six other race categories, showcasing growing diversity among Natives. Those who added black, white or both as a personal identifier made up 84 percent of the multi-racial group.

Tribal officials and organizations look to Census data for funding, to plan communities, to foster solidarity among tribes and for accountability from federal agencies.

The bump in the multi-racial group from 1.6 million in 2000 to nearly 2.3 million in 2010 was higher than that of those who reported being solely of Native descent.

“When information comes out and is available for our tribes and tribal communities, we have a lot of issues going back to identity,” said Mellor Willie, executive director of the National American Indian Housing Council. “Who is Indian?”

The Blackfeet Nation in Montana had the highest proportion of people who reported being part of more than one racial group or tribe at 74 percent. Among Alaska Native groups, the Tlingit-Haida had the highest proportion of mixed-race Natives at 42 percent.

The number of Natives identifying with at least one other race increased in all but three states from 2000 to 2010, the Census reported.

The Census figures, released during a presentation at the National Museum of the American Indian in Washington, D.C., also include people living in the United States who consider themselves indigenous to Central and South America. Tribal officials say it’s the best snapshot of Native people available, but the data is often supplemented with tribal enrollment figures or other surveys and studies.

Amber Ebarb, with the National Congress of American Indians’ Policy Research Center, said the data also is used to track trends among states and regions, determine the mobility patterns of Natives and figure out how best to deliver services to Natives or conduct outreach.

“It’s kind of a function of geography,” she said. “There’s this trend where single-race American Indians live in tribal communities and multi-race Natives live farther.”

Some tribes were less diverse. Of the 34,000 people who identify as Yup’ik, an Alaska Native tribe, 29,000 said they were affiliated with no other race. The Navajo Nation, whose reservation stretches into New Mexico, Utah and Arizona, had the highest proportion of people who identified as Native and nothing else at 86 percent of its 332,000 population, Census officials said.

The Navajo Nation comes in second in population behind the Cherokee’s 819,000 population, 65 percent of whom identify with another race.

Census Director Robert Groves said the bureau has projected that the overall Native population will increase to 6.8 million in 2030 and about 8.6 million in 2050. Both multiracial Natives and Natives alone grew at a rate higher from 2000 to 2010 than the U.S. population at large.

Among other findings:

—Seventy-eight percent of Natives live off tribal reservations but many live in counties close to reservations, particularly throughout the West, including Oklahoma.

—The majority of Natives live in 10 states: Arizona, California, Florida, Michigan, New Mexico, New York, North Carolina, Oklahoma, Texas and Washington.

—The population of multi-racial Natives jumped by more than 50 percent in 18 states, and by more than 70 percent in North Carolina, Delaware and South Dakota.