If there’s anything productive to come from his recent Twitter storm, President Trump’s recent crude attacks on Baltimore Congressman Elijah Cummings have succeeded in bring necessary attention to the increasingly tragic state of our cities. Baltimore’s continued woes, after numerous attempts to position itself as a “comeback city,” illustrates all too poignantly the deep-seated decay in many of our great urban areas.

Baltimore represents an extreme case, but sadly it is not alone. Last year our three largest urban centers — New York, Los Angeles and Chicago — lost people while millennial migration accelerated both to the suburbs and smaller, generally less dense cities. These demographic trends, as well as growing blight, poor schools, decaying infrastructure and, worst of all, expanding homelessness are not merely the result of “racism” or Donald Trump, but have all been exacerbated by policy agendas that are turning many great cities into loony towns.

Politics run amok

Take tech rich San Francisco, where decades of tolerance for even extreme deviant behavior has helped create a city with more drug addicts than high school students, and so much feces on the street that one website has created a “poop map.” In Southern California’s far more proletarian city of Los Angeles, we have a downtown filled with overbuilt, overpriced apartments and is, like Baltimore, being overrun with rats. A UN official last year compared conditions on the city’s Skid Row to those of Syrian refugee camps.

One would think such nasty problems would spark something of a political rebellion, as seen in previous decades with the rise of successful, pragmatic mayors — Bob Lanier and Bill White in Houston, Rudy Giuliani and Michael Bloomberg in New York, and Richard Riordan in Los Angeles. But so far, at least, many of today’s big city mayors seem more interested in bolstering their “resistance” bona fides than governing effectively.

Los Angeles’ Eric Garcetti, for example, speaks enthusiastically about his own “green new deal” and turning the city into a transit Valhalla even as blight and homelessness expand inexorably. The mayor is less rhapsodic about practical things that people actually need, such as decent roads, reliable water supply or electricity.

Economic growth generally is not much of a priority for the woke urban political class. In New York, Rep. Ocasio Alexandria Cortez’s allies succeeded in driving Amazon’s new headquarters out of her district. Meanwhile her socialist comrades in Seattle have helped persuade the on-line giant to relocate more of its employees out to a massive new building in the suburb of Bellevue while the Emerald City hosts a rising homeless population.

The demographics of ultra-progressivism

Ironically, this far-left trend partially can be traced to the post-2000 urban resurgence, sparked by the now unappreciated pragmatic mayors who made cities safer and more business friendly. Safe streets and thriving businesses lured large numbers of young people, many well-educated and mostly liberal, to the urban core in numbers not seen for generations.

Yet since the 1970s the middle class in cities has been in a precipitous decline while poverty has remained stubbornly high. Philadelphia’s central core, for example, rebounded between 2000 and 2014, but for every one district that gained in income, two suffered income declines. In 1970, half of Chicago was middle class; today, according to a new University of Illinois study, that number is down to 16 percent. Meanwhile, the percentage of poor people has risen from 42 to 62 percent.

The most attractive blue cities — led by New York, San Francisco, San Jose, Los Angeles and Boston — now suffer, according to Pew research, the largest gaps between the bottom and top quintiles of all U.S. cities.

The post-2000 urban success increased housing prices but failed to create a new stable urban middle class. Most young urbanites don’t stay long enough to build long-term communities; once they hit the family formation period in their thirties, they still largely depart for the suburbs. As the Atlantic recently noted the number of babies born in Manhattan this decade dropped nearly 15 percent; already home to a majority of single households, the nation’s premier urban center could see its infant population cut in half in 30 years.

Remaking urban politics

The new demographics have hollowed out the political middle in most cities.

The old urban middle class leaned Democratic, but they were largely interested in practical outcomes — like paved roads, fixed lights, and access to jobs. Their departure, and replacement by temporary hipster populations, has helped insulate city governments from constituents who would be most adamant about reforming usually failed school districts or demanding improvements in public infrastructure or maintaining public order.

Electoral engagement has faded in most cities, with turnout for mayor averaging 15 percent for mayoral races in our most populous cities. In Los Angeles, the 2013 turnout that elected progressive Eric Garcetti was roughly one-third of that in the city’s 1970 mayoral election. Garcetti’s 2017 re-election boasted a similarly low turnout.

The prime beneficiaries of these changes have been the well-organized. Rep. Alexandria Ocasio Cortez’s primary victory rested on 16,000 votes out of a total Democratic registration of almost 215,000. She won not by sweeping the proletarian or minority masses, but marshalling the votes of white young educated hipsters. These voters are driving the rise of far-left socialists in other cities, including Denver, who seek to replace not Republicans but more traditional liberal Democrats.

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The new urban politics threatens the future of family neighborhoods, local entrepreneurial ventures as well as an apolitical, exuberant diversity. Immigrants and aspiring minorities want good schools, safe streets and less onerous regulation. Resolutions on sanctuary cities, condemnations of Trump tweets, social justice demands and boasts about combating climate change do little to improve tangibly the realities of cities like Baltimore or even superstars like San Francisco, Washington, and New York.

Only when grassroots people and concerned businesses decide to challenge the urban status quo and the virtue-signaling political class can decay and the relentless bifurcation of our cities be reversed. After all, large and powerful companies, like Amazon, can always pack up and migrate to less insane political environments. But those with a strong stake in the local economy and neighborhoods have fewer options. It will be up to them, to restore our cities’ historic role as places for both families and middle-class economic aspiration.

Joel Kotkin is the R.C. Hobbs Presidential Fellow in Urban Futures at Chapman University in Orange and executive director of the Houston-based Center for Opportunity Urbanism (www.opportunityurbanism.org).