WASHINGTON — This city, the country’s first to have an African-American majority and one of its earliest experiments in black self-government, is passing a milestone.

Washington’s black population slipped below 50 percent this year, possibly in February, about 51 years after it gained a majority, according to an estimate by William Frey, the senior demographer at the Brookings Institution.

The shift is passing without much debate, but it is leaving ripples of resentment in neighborhoods across the city, pitting some of the city’s long-term residents, often African-American, against affluent newcomers, most of whom are white, over issues as mundane as church parking and chicken wings.

“You can’t help but look around and see the face of the community changing before your eyes,” said Tom Sherwood, co-author of “Dream City: Race, Power, and the Decline of Washington, D.C.”