Even in New York, where so many people pride themselves on their political engagement, hyperlocal elections rarely generate much interest either in terms of buzz or turnout, and they lead to surprising results even less often. But a City Council race on Tuesday managed to bring uncommon suspense. By Wednesday the contest had been called in favor of an X-ray technician who became the first Republican to win public office in the Bronx in nearly 20 years, a place where Democrats outnumber Republicans by more than 10 to 1.

The relevant seat encompasses the northeastern quadrant of the borough, much of it on the shoreline of the Long Island Sound and Eastchester Bay, where a certain kind of urban denialism, largely indifferent to political affiliation, remains sacred. Two decades ago, the area underwent a rezoning that allowed for existing three-family houses to be converted to two-family houses and for those about to be built to be detached. This had the effect of further suburbanizing an area that had long been neglected by mass transit and already included within its borders a neighborhood assertively named Country Club.

The trouble for the incumbent Democrat, Marjorie Velázquez, who won her last election with slightly more than two-thirds of the vote, began when she put herself on the wildly unpopular side of the density question. Until last year she had shared the community’s opposition to a rezoning proposal that would bring four mixed-use buildings with 349 apartments, nearly half of them rent-regulated, to an area around Bruckner Boulevard. Citing the city’s ongoing housing crisis, she eventually changed her mind. The rate of homeownership in the neighborhood most directly affected is significantly higher than it is citywide, but roughly half of the people who live in it rent and are spending more than 30 percent of their income on rent.

With the support of Ms. Velázquez, the plan moved forward to unanimous approval by the City Council. Her constituents did not respond well. A few days before the vote, they protested outside her office demanding that she be voted out. At one point a billboard truck drove by attacking her as the “Benedict Arnold” of Throgs Neck.

This was last fall; by February a neighborhood group calling itself the Bronx Coalition Against Upzoning sued the city to stop the project. Among the concerns raised was the issue of “neighborhood character,” the pushcart bearing nearly all objections to development in the city. Plaintiffs argued that the proposed buildings would seem out of place in a neighborhood of one- and two-story houses and “destroy the streetscape where they exist.”

But the area under scrutiny is not Harlem or Forest Hills or Ditmas Park. Much of the housing stock is comparatively new, distinguished neither by history nor architectural singularity. Landmark districts coexist with high-rises throughout the city, and in this instance the proposed buildings would not exceed eight stories. The suit was dismissed by a Bronx judge.

This gave Kristy Marmorato almost all that she needed to win. “If there is an issue that everyone of any political ideology could rally around, it’s land use in this community,” Matthew Cruz, the district manager of the local community board told me. “These residents are quick to remind me that this is a space they carved out for themselves in this part of the city. They might work in Manhattan, but they are here to get away from that.”

More than anything, Mr. Cruz believed, the outcome was payback for the incumbent, an expression of fear that the Bruckner rezoning, although now a foregone conclusion, would bring similar efforts on any block unless there was strong political resistance against it.

Ms. Marmorato, in fact, entered the race as a resister. Early on, she explained her interest in running to The Bronx Times. “I was a little girl and I knew who Ronald Reagan was because my brother was writing letters to him,” she said. That brother, Michael Rendino, became the chairman of the Bronx Republican Party.

But this adjacency is not what got her interested apparently. Instead, it was a plan to house people coming out of Rikers Island in an empty building that was part of the Jacobi Medical Center, near where she lived. She opposed it in favor of a safe house for victims of domestic violence, and it was at this point, she said, that she became more civically driven, shocked by the disconnect between what was happening at the community level and what was happening at City Hall.

What was happening downtown was Eric Adams and his “City of Yes” — yes to construction, and yes to 32-foot cellphone towers on the Upper East Side, the subject of indignant protest just this past week. From the beginning, the mayor had decried the NIMBYism directed at the Throgs Neck venture, pointing out that the neighborhood had added only 58 units of affordable housing in the past decade. Voters in search of the City of No were not going to get it. But in the absence of that, they would try, at least, for the City of Maybe Not.