President Donald Trump is not the first politician to invoke rat infestation in an attempt to demean black neighborhoods. In the summer of 1967, President Lyndon Johnson asked Congress for $40 million to support rat control in communities engaged with his Model Cities program. Model Cities and the Rat Extermination Act were part of Johnson’s agenda to invest in black neighborhoods long deprived of resources for housing, infrastructure and economic development by segregationist policies.

Black leaders like Whitney Young and the Rev. Martin Luther King Jr. urged a multi-billion dollar program of urban redevelopment, but Congress even refused many of Johnson’s more modest requests. The Rat Extermination Act was one small example of this: When it came up for debate, Congressmen from rural districts laughed it off the floor. Rep. James Broyhill of North Carolina drawled, “the rat smart thing to do is to vote down this civil rats bill, rat now.”

Several representatives insisted that neighborhoods struggling with rats should take responsibility for the problem themselves. Rep. Delbert Latta of Ohio sniped, “The matter of putting out a little bit of rat poison should not be requested of the Federal government.” A year earlier, Latta had requested funding to poison starlings in Ohio. Congress was already spending more for pest control that benefited farmers and suburbanites than for urban rat control.

As in President Trump’s tweets, the racial innuendo was obvious: Broyhill, Latta and and other rat control opponents in Congress blamed rat infestation on black communities. Some black activists also saw the rejection of federal rat-control funding as retribution for the civil uprising in Newark, which ended just a few days before the bill came up for debate on July 20th, 1967.

Later that year, rural members of the Wisconsin Assembly mocked a Milwaukee delegate who proposed adding rat control funding to a predator control bill.

All urban neighborhoods are potential rat homes because these creatures are well-adapted to humans and can take advantage of any crack or crevice to access habitat, any scrap of waste for food. But rats are frequently a serious problem for neighborhoods struggling against the many legacies of racial segregation. Racist urban policies created environments where rats could thrive, and infestations are often neither the fault of local communities nor a matter they can solve with local resources alone. To understand why West Baltimore residents may endure greater exposure to rats, we must turn to the origins of racial segregation policies in the early 20th century.

From realtors to the office of the mayor, Baltimore’s leaders long denied blacks (and Jews, who were not then considered white) access to white neighborhoods and deprived non-white neighborhoods of resources to maintain sound housing conditions. Blacks had few choices about where they lived. In 1935, the sociologist Ira Reid observed that landlords only rented to blacks “at the last stage of residential occupancy,” after a succession of white residents had left homes severely depreciated. Redlining discouraged loans for prospective buyers and for owners seeking money for upkeep. Rat populations grew on disinvested blocks as loose boards and cracked foundations opened up habitats dangerously close to human residents.

Then and now, Baltimore residents have invested their own time and money in renovations, planted gardens to displace rat burrows and organized community clean-ups. Many have also protested housing discrimination and demanded greater public investment in affordable homes. The city has taken small, but as yet insufficient, steps to meet these demands through the years.

For example, in the 1940s and ’50s, the city provided a modest revolving fund to support code enforcement. Johns Hopkins ecologists found that rat populations dropped and stayed low on blocks where this program underwrote thorough repairs. Sound housing conditions and low rat numbers were sustained even longer where the city helped tenants take neglectful landlords to court and provided continued resources to property owners. Johnson’s rat control proposal, eventually funded months later, had similar aims for cities across the U.S. But in Baltimore and at the federal level, funding was never sufficient to correct all the damage done by racist policies. Meanwhile, so-called urban renewal programs encouraged rats to spread from demolished buildings.

Baltimore is far from unique in its history of segregation and official neglect that expanded ecological niches for rats and imposed the stigma of rats upon communities of color. So far, public and private sectors at all levels have fallen short of atoning for this history, in spite of communities’ demands.

Racists like President Trump will never understand this, but perhaps the rest of us might add our voices to affected communities’ calls for funding to redress the injustices that rats are so well-adapted to exploit.

Dawn Biehler (dbiehler@umbc.edu) is an associate professor at the University of Maryland, Baltimore County.