Opinion | The Deep, Tangled Roots of American Illiberalism

Most worrisome, the Ku Klux Klan, energized by anti-Catholicism and antisemitism as well as anti-Black racism, marched brazenly in cities great and small. The Klan became a mass movement and wielded significant political power; it was crucial, for example, to the enforcement of Prohibition. Once the organization unraveled in the late 1920s, many Klansmen and women found their way to new fascist groups and the radical right more generally.

Sidelined by the Great Depression and New Deal, the illiberal right regained traction in the late 1930s, and during the 1950s won grass-roots support through vehement anti-Communism and opposition to the civil rights movement. As early as 1964, in a run for the Democratic presidential nomination, Gov. George Wallace of Alabama began to hone a rhetoric of white grievance and racial hostility that had appeal in the Midwest and Middle Atlantic, and Barry Goldwater’s campaign that year, despite its failure, put winds in the sails of the John Birch Society and Young Americans for Freedom.

Four years later, Wallace mobilized enough support as a third-party candidate to win five states. And in 1972, once again as a Democrat, Wallace racked up primary wins in both the North and the South before an assassination attempt forced him out of the race. Growing backlashes against school desegregation and feminism added further fuel to the fire on the right, paving the way for the conservative ascendancy of the 1980s.

By the early 1990s, the neo-Nazi and Klansman David Duke had won a seat in the Louisiana Legislature and nearly three-fifths of the white vote in campaigns for governor and senator. Pat Buchanan, seeking the Republican presidential nomination in 1992, called for “America First,” the fortification of the border (a “Buchanan fence”), and a culture war for the “soul” of America, while the National Rifle Association became a powerful force on the right and in the Republican Party.

When Mr. Trump questioned Barack Obama’s legitimacy to serve as president, a project that quickly became known as “birtherism,” he made use of a Reconstruction-era racist trope that rejected the legitimacy of Black political rights and power. In so doing, Mr. Trump began to cement a coalition of aggrieved white voters. They were ready to push back against the nation’s growing cultural diversity — embodied by Mr. Obama — and the challenges they saw to traditional hierarchies of family, gender and race. They had much on which to build.