The District is growing progressively younger and whiter, as a steep rise in the number of young white adults has outpaced the growth in African American residents, new census statistics show.

The city gained about 6,500 non-Hispanic whites in 2012, accounting for almost half the year’s total growth, and they now make up 35.5 percent of the District’s 632,000 residents.

In contrast, the city last year gained 1,700 non-Hispanic black residents, who make up 48.6 percent of the population. If the 9,300 black Hispanics who live in the city are counted, African Americans maintain the slight majority of 50.05 percent.

One in 10 residents is Hispanic, both black or white, while Asians account for less than 4 percent of the population.

The 2012 population estimates from the Census Bureau show a continuation of trends that have dramatically changed the District’s demographic characteristics over the past decade. Although African Americans remain the largest single resident group, their numbers have been on a long slide since the peak in 1970, when seven in 10 District residents were black and people proudly said they lived in “Chocolate City.”

How the U.S. population changed in 2012

Over a little more than a decade, the city has rebounded and reversed a population slide that began after residents started moving out to the suburbs. In the past two years, the city’s population has soared by about 30,000 people. That is 10,000 more residents than it gained in the decade preceding it.

The shift has been as much generational as racial. The bulk of the growth since 2010 has been among people between the ages of 25 and 39. That group has contributed to a baby boomlet, adding 6,000 more children younger than 5. As a result, the median age has dipped slightly, from 33.8 in 2010 to 33.6.

The figures for the District also illustrate some of the complexities of determining race in an era when one of the fastest-growing groups in the nation is people who consider themselves multiracial.

The District’s black population, for example, does not include any of the almost 16,000 residents who say they are two or more races. Ben Bolender, a demographer with the Census Bureau, said that because the census does not ask people to pick a primary identity, there’s no way to determine whether the 9,300 people who said they were both black and Hispanic think of themselves more as one than the other.

But even if all black Hispanics in the District are counted as part of the African American population, demographers agree it is probably a matter of time before they slip below the 50 percent milestone, if they haven’t already.