The black population in the District has lost its outright majority for the first time in more than half a century, in a population shift driven by a higher cost of living and an influx of younger whites into the nation's capital, new census data released Thursday show.

The shift makes D.C. unique among the nation's major cities, said Lisa Sturtevant, assistant research professor at George Mason University's Center for Regional Analysis.

"Lots of cities grew in last few decades," she said. "Washington, D.C. was the only city where growth was driven by the white population."

The number of non-Hispanic whites living in the District since data were collected in April 2010 has grown by 4 percent to total more than 218,000 as of July 2011, according to the new Census Bureau data. Meanwhile, the number of blacks stayed relatively flat but fell from just over half of the population to 304,203 people, or 49.2 percent.

The white population now makes up 35.3 percent of the city's total pie. This marks the highest percentage of whites living in the District since the 1960s, when whites were leaving the city for the region's more spacious suburbs.

Though Washington was a natural attraction for freed slaves following the Civil War, the city remained majority-white until 1960, when blacks made up more than 53 percent of the residents, according to census data.

The black population peaked in 1970 at more than 71 percent of the population.

But now, because of the urban revitalization that began in cities more than a decade ago, housing prices are climbing in the District and lower-income residents are being priced out of the District. Since 2000, nearly 40,000 blacks have left D.C., according to census data.

Mark Mather, a demographer with the Population Reference Bureau, said it's likely whites will continue to gain a larger share in the District.

"I can't think of any economic or social trend that would lead to a reversal of what we're seeing right now," he said. "There hasn't been a lot of progress made in terms of retaining African-American families in the city. I think we're going to continue to see out-migration into Prince George's County."

Mayor Vincent Gray and Council Chairman Kwame Brown were unavailable for comment Thursday evening.

Meanwhile, the growing white population in the District isn't necessarily coming from the suburbs, as Sturtevant noted the population there among whites has stayed relatively flat. Rather, it's young singles driving the bulk of the growth as the city's job market remained among the strongest in the country -- even through the lean recession years.

Recently, though, families with young children have been adding to the white population's growth, according to Mather.