More than 39,000 blacks have left the district in the past decade while the non-Hispanic white population increased from 50,000 to 209,000, nearly one third more than a decade earlier, The Washington Post reported.
The district's black population is now about 301,000; the overall population of Washington is 601,700.
The change is largely the result of nearly 15 years of gentrification, the Post report said. The change has made it harder for working-class families to live in the city, it said.
"Clearly, D.C. is one of the most polarized cities by income and education, in the country," said Rodrick Harrison, a Howard University demographer who spent a decade with the Census Bureau. "You have this unusually large college educated population. And then you have a population that is largely black, with high school degrees or less."
The city's black population is dropping about 1 percent a year, the report said.