The continuing tragedy of the coronavirus pandemic has offered an unexpected opportunity to change American voting fundamentally through the adoption of vote-by-mail policies. President Trump, however, is sounding the alarm — or, more accurately, the dog whistle.

On Thursday, he tweeted that mail voting was a “catastrophic failure” with no accurate count, warning that 2020 would be “the most INACCURATE & FRAUDULENT Election in history.” He even floated delaying the election, a prospect that was quickly denounced by Republicans and Democrats alike.

Vote-by-mail solutions have long made sense as a way of ensuring people’s voting rights, and they make even more sense now, when they would protect citizens from potentially deadly exposure to covid-19 at the polls. Trump’s opposition to them must be understood as the most recent act in a long, remarkably consistent historical drama defined by the unremitting commitment to impeding non-White voters from exercising their right to political participation. This political tradition dates back to the advent of Black suffrage and the ratification of the Fifteenth Amendment.

In the wake of the Civil War, Black men began exercising their right to vote in the South. Abolitionist leader William Lloyd Garrison was awed by “this wonderful, quiet, sudden, transformation of four millions of human beings from … the auction-block to the ballot-box.” Southern Whites and ex-Confederates, however, were largely horrified at this change. It, indeed, was a “transformation” for them as well. They lost their monopoly on political control.

These new voters brought formerly enslaved people to public office. In “Freedom’s Lawmakers,” historian Eric Foner estimates that approximately 2,000 African American men served at the local, state and federal levels of government during Reconstruction. This was a complete reversal of the social order. Local police forces were no longer entirely White, and several Black Southerners became election officials. Black hands counted White votes and vice versa.

In this period, the Ku Klux Klan formed, dedicated to terrorizing African Americans, often with the aim of keeping them from the polls. In 1892, the Chicago Tribune interviewed an anonymous Wall Street banker who had been a high-ranking member of the terrorist organization during its early prominence in the South after the war. He was unequivocal about its founding purpose: “[It] formed to guard against Negro supremacy in the South … A Presidential election was near at hand and it was of the highest importance for the Whites to take such steps as to prevent the Negroes from asserting their superiority of numbers so as to gain control of the southern States.”