In 2014, Jonathan Auerbach, a statistician studying at Columbia University, analyzed rodent complaints made to New York’s 311 call system. His goal was to create a census of the rat population—not to become a footnote in Presidential politics. His estimate of just over two million rats in the city would have been horrifying but for the long-held belief that New York housed equal numbers of rats and humans, as if a municipal sponsor program had assigned each of the eight million New Yorkers a muck-dwelling murine counterpart. The good news was that every four New Yorkers shared just one rat.

At the time, the data was touted as settling the continual debate over the size of New York’s rat population. But it’s emblematic that it is now pertinent to Donald Trump’s defamatory attack upon (yet another) American constituency. Trump’s most recent Twitter invective spree targeted Representative Elijah Cummings, a Maryland Democrat and the chair of the powerful House Oversight Committee, whose district includes parts of the city of Baltimore, and whose committee is conducting multiple investigations of the President. Trump referred to Cummings’s district, Maryland’s Seventh, as a “disgusting, rat and rodent infested mess.” The Baltimore Sun shot back with an editorial headlined “Better to have a few rats than to be one.” Trump does not possess great reserves of self-awareness, or else he would have chosen his insult more carefully. Last year, the pest-control company Orkin released its annual list of the “rattiest” cities in the United States, based on how many new rodent treatments the company performed. Baltimore, despite some noted improvements, made the list for the third year in a row, coming in at ninth place. New York came in third—with, again, one rat for every four people. (Chicago came in first, for the fourth year in a row.)

“No human being would want to live there,” Trump said of Baltimore on Twitter, implicitly questioning the humanity of the six hundred thousand human beings who do, in fact, live there. A little more than twenty per cent of the people in Baltimore are under the age of eighteen. How those young people are to find inspiration, cultivate pride in their communities, or gain a sense of their own potential when the President of the United States has called their home unfit for human habitation is a matter that Trump left unaddressed, if that concern even grazed his conscience. His use of the term “human” is implicit code for “white”—it recalled the language of the nineteen-nineties-era Los Angeles Police Department, which often referred to shootings in which both the perpetrator and victim were minorities as N.H.I.s, for “no humans involved.” On Saturday, the CNN anchor Victor Blackwell struggled to maintain his composure as he spoke about Baltimore, the city he grew up in; the fully American aspirations of the people who live and work there; and the loaded, racist ways in which Trump has used the term “infested.” Five of the people the President has most recently singled out for condemnation, all members of the House of Representatives, are members of minority communities.

There are discernibly more rats in New York than there are in Baltimore, but some of the rats in Baltimore have effectively been enabled by New Yorkers—more specifically, Jared Kushner, the New York real-estate baron and Trump’s son-in-law. The Washington Post reports that Kushner’s company has owned some nine thousand apartments in Baltimore that generated, in a single year, more than two hundred complaints of disrepair, code violations, and rodent infestation. The company has been sued and issued financial penalties for failing to address these concerns in a timely manner.

All of this is immaterial to Trump. His vision of the disparate worlds that the recent targets of his ire come from is uniformly dystopian—a free association of skin color with filth and crime. As President, he has attacked an untold number of individuals—actually, we have some idea of the number—but the racist themes in his screeds are hard to miss. In 2017, he attacked John Lewis, the civil-rights-movement veteran and Georgia congressman, saying that the Atlanta district that Lewis represents is “crime infested” and “falling apart.” The district is actually home to one of the largest concentrations of college-educated and affluent black people in the country. But that fact was insignificant to Trump, whose rhetoric betrays a kind of mass racial profiling: Lewis is black and so are the majority of his constituents, and we all know what kind of conditions those people live under. Trump said as much in his left-handed appeals to black voters in 2016. “Horrible education, no housing, no homes, no ownership, crime at levels that nobody has seen,” he said. “What the hell do you have to lose?” Self-respect, apparently.

Trump’s use of “infestation” is another metaphor meant to cloak his own culpabilities. He railed about Washington, D.C., being a swamp of corruption before installing his own regime of Boss Tweedian indulgences, with multiple Cabinet members accused of ethics violations or graft. He launched his Presidential campaign decrying Mexican “rapists,” only to be accused of sexual harassment or assault by more than twenty women. He frequently bashes black politicians for the poverty in inner cities, although these are places whose well-being he, as President, is responsible for as well. He is not alone in that practice: Republican criticism of Democratic leadership has frequently pointed to poverty in cities where minority populations overwhelmingly vote for Democrats. But ten of the twelve poorest states in the union—Alabama, South Carolina, West Virginia, Oklahoma, Kentucky, Arkansas, Tennessee, Idaho, Florida, and Mississippi—are not only led by Republican governors but have legislatures in which the G.O.P. has majorities in both houses. On Sunday morning, when Trump’s acting chief of staff, Mick Mulvaney, appeared on Fox News to defend Trump, he claimed that he would have been “fired” if there were poverty in his former district, South Carolina’s Fifth, like there is in Baltimore. Critics on social media hastened to point out that Mulvaney’s district was actually slightly poorer than Cummings’s is.

The Baltimore Sun further noted that, when Trump referred to the communities that Cummings represents, he omitted more affluent ones such as Ellicott City and Baldwin in favor of the poorer areas of Baltimore—places that he could ridicule en route to making his hyperbolic point. This is the essence of racism: an epidermal association of a group of people with the worst possibilities, even when—especially when—available evidence points to the contrary.

The human aversion to rats is ancient and abiding. They are vectors of Clostridium difficile, salmonella, E. coli, and Leptospira—consumers of refuse and carriers of pestilence. The evidence of their presence is noted by burrows in the earth; droppings, which may cause asthma; and the greasy trail that they frequently leave in their wake. They inspire disgust for good reason and yet, for all their liabilities, they possess a singular virtue that Donald Trump lacks: they make no attempt to deny what they actually are.