You may have heard that all true Christians must vote the same way, but Christians have almost never manifested that political cohesion in American history. Christians have often divided along ethnic and geographic lines, reflecting the role of slavery, the Civil War, and civil rights. The truth is that traditionalist Protestant voters in America—if we don’t mean just whites—have almost never been unified.

Until the 1960s people of color—especially African Americans—could not count on being able to vote, so this analysis is somewhat limited to whites. Even if you only consider whites, however, conservative Christians have often voted for candidates depending on what region of the country they lived in, rather than voting as a faith-oriented bloc.

In 1800, the first truly divisive presidential election in our history, evangelicals may have been slightly more likely to support the religious skeptic Thomas Jefferson, a champion of religious liberty, than the Unitarian John Adams, who was friendly to state support for religion. But region was a greater predictor of voting patterns than differences of faith in 1800, with white Southerners overwhelmingly supporting Jefferson, seeing him as a defender of their economic interests. There were also major differences between denominations, with Baptists more likely than (for example) Congregationalist evangelicals to support Jefferson.

It may be that the closest we have ever gotten to unified support of traditionalist Protestant voters for one party was for the Whigs, from the 1830s to the 1850s. The Whigs were the party of moral reform in causes such as temperance, so they enjoyed considerable support from evangelicals in the North and South. William Henry Harrison, the first Whig elected president, received broad-based electoral votes in 1840, including victories in the majority of Southern states. Most American blacks could not vote before the Civil War, of course. In Northern states, the small number of black voters often supported the Whigs, since northern Whigs tended to be antislavery. (Southern Whigs were generally proslavery.)

African American voting in the South saw a brief flowering after the Civil War, and they were overwhelmingly Republican because of the memory of Lincoln and emancipation. By the late 1870s, white Democrats “redeemed” the South, which included barring blacks and white Republicans from voting. Northern blacks who retained the vote tended to vote Republican until the 1930s, when many African Americans became part of FDR’s New Deal coalition. White Southerners, including evangelicals, overwhelmingly supported Democrats for a century after the Civil War.

That began to change in the aftermath of the LBJ-sponsored civil-rights legislation of the mid-1960s, when many Southern Democrats, such as U.S. Senator Strom Thurmond of South Carolina, switched to the GOP. Thurmond was one of the most prominent Southern Democrats in 1964 to support Republican presidential candidate Barry Goldwater, who opposed the Civil Rights Act. The year 1976 and the election of Georgia Democrat Jimmy Carter was the last cycle in which many Southern African Americans and whites voted for the same presidential candidate. By that time, strong majorities of white Northern evangelicals already supported GOP nominees, starting with the (vaguely religious) Dwight Eisenhower in the 1950s.

The past 50 years have seen the emergence of more rigid ethnic voting patterns in America, replacing older regional alignments. Over the past half-century, whites (especially self-identified evangelicals) have tended to support Republicans, and African Americans (including traditionalist Protestants) have overwhelmingly supported Democrats. The largest ethnic group whose conservative Christian voters are still “up for grabs” are Latinos.

So when insider Republican evangelicals such as Franklin Graham tell us that Christians must vote Republican, one of the great unaddressed questions is why so many traditionalist Christians, especially African American Christians, take an entirely different view? In any case, political disagreement among American Christians has almost always been the norm, and that will certainly remain the case in 2020.

For more on evangelicals’ history of political engagement, see my book Who Is an Evangelical? The History of a Movement in Crisis.