Rev. Martin Luther King Jr.’s assassination on April 4, 1968, helped usher in the passage of the Fair Housing Act (FHA), a law that promised to not only stop unjust discrimination but also reverse decades of government-created segregation.

The FHA, which made discrimination on the basis of race, color, national origin, religion, sex, familial status, and disability illegal in the process of buying and selling homes, had already failed to pass Congress in two earlier versions. As Michelle Adams wrote for the New Yorker, the 1968 version would likely have met the same end if not for the political impact of the assassination.

But just a few months after the act’s passage, Richard Nixon was elected, and, as Nikole Hannah-Jones explained, the federal government’s “betrayal” of the FHA’s promise began. Nixon’s Department of Housing and Urban Development Secretary George Romney did attempt to use the FHA to meet its goal and actually desegregate white communities, telling “HUD officials to reject applications for water, sewer, and highway projects from cities and states where local policies fostered segregated housing.” But Nixon put a quick stop to this policy. And as Hannah-Jones documents, he wasn’t the last; since then, “a succession of presidents — Democrat and Republican alike — followed Nixon’s lead.”

In the 21st century, segregated communities are kept that way not through laws that explicitly attempt to keep certain areas white but through a more insidious method — exclusionary zoning and land-use regulations that make it illegal to build affordable types of housing, laws that allow wealthy Americans to block things from being built, and a failure to consistently use federal civil rights laws to desegregate.