So politicians, policy wonks and pundits have all spent a lot of time agonizing over what to do about gentrification. They have called for reforms to permitting and zoning rules to make it easier for developers to build new housing, or for subsidies to the people being priced out, or both. In hindsight, we spent surprisingly little time worrying about what would happen to cities without gentrification.

Yet here we are in 2024, and I’m much less worried about gentrification than I am about what you might call gentrification whiplash: the uncomfortable conditions that result when a headlong rush into urban real estate suddenly stops, or even goes into reverse.

This now seems like a real possibility in many places, including my own beloved D.C., which is beset with three major issues at once. Demand for office space has cratered thanks to remote work. Demand for residential real estate has shifted outward to the suburbs, as proximity to the office has become less valuable. And crime keeps soaring to new heights; in 2023, homicide hit 20-year highs in D.C., while car theft reached levels not seen since 2007.

If this trend continues, people who have money and options will do what they did in the middle of the 20th century: decamp for places where they don’t have to spend so much time worrying about being robbed or shot.

Yet the response of my local officials has been curiously lackadaisical. Although violence has been a growing problem since 2020, arrests in 2022 were down by almost half from 2019, prosecutions had fallen even further, the D.C. police’s operating budget shrank by almost 13 percent and the number of officers was falling toward its lowest in about 50 years. Only this past fall did Mayor Muriel E. Bowser finally push through a package of reforms aimed at reducing crime.

So let us add a fourth problem to my city’s woes: city officials who have for years been collecting a sort of hidden subsidy from gentrification, which made their jobs easier in many ways — and stands to make the whiplash worse. We are facing the biggest urban crisis in 50 years with politicians who are used to playing on Easy Mode, which is the policy equivalent of driving without a seat belt.

For the past two decades, if you were overseeing a reasonably successful city like Washington, your tax base kept improving no matter what you did, as richer people replaced poorer ones. In 2006, when I moved to D.C., total tax revenue, net of dedicated taxes, was $4.2 billion (about $6.3 billion in today’s dollars). In 2022, the city collected approximately $8.6 billion ($8.8 billion in 2023 dollars). Of course, the population has increased since 2006 — but not by 40 percent.

Meanwhile, the people who were moving in needed less from the government than the people who were being forced out. The newcomers didn’t need subsidized health care or child care, or the city to arrange a tutor for their kid struggling with math. They were also much less likely to suffer from difficulties associated with poverty, including substance abuse and untreated mental illness — or to generate associated problems such as crime and child abuse.

We frequently talk about the government learning to do more with less, but gentrifying cities got to do less with more: It doesn’t take as much money and ingenuity to educate or police the prosperous middle class as it does to provide those services to a marginalized community, so government didn’t have to be nearly as good at many of its jobs. Yet because the population was less needy, it actually looked as if those services were improving rapidly, if you scanned crime statistics or test scores.

Of course, gentrification didn’t actually solve many of those problems; it just displaced them, while tipping some of the most vulnerable onto the streets. But politicians appeared to be solving them, creating an illusion of competence that might have fooled even the politicians themselves.

This went on for so long that people took it for granted, voters and politicians alike. We got progressive mayors, progressive district attorneys and progressive council members who pursued their laudable goals on the assumption that no matter what they did, crime would keep falling and public coffers would keep overflowing.

Now this illusion is punctured. Ever-increasing urban housing demand cannot be taken for granted, nor can any of the benefits that come with it. City officials can no longer count on gentrification to export their problems to another Zip code; they will have to get better at actually solving them.