“Tariffs are the greatest!” President Trump crowed on Twitter on Tuesday morning. If that represents a break from contemporary Republican orthodoxy, it’s a message other GOP presidents once embraced. Trump has previously quoted William McKinley declaring that tariffs made Americans lives “sweeter and brighter and brighter and brighter.” (For the record, McKinley only said “brighter” once.) And after Congress passed the Tariff Act of 1909, William Taft declared it “the best bill that the Republican party ever passed.”

But the voters disagreed, vehemently. In the next two elections, they obliterated the GOP’s congressional majority, crushed Taft’s reelection hopes, and sent the party into a tailspin. Tariff policy was one of the most divisive issues in American politics, because its costs and benefits were unevenly distributed. Protectionist policies offered windfalls to large corporations while burdening small businesses and farmers with higher prices. That stirred bitter resentments in less industrialized, agricultural regions, fueling North-South discord before the Civil War, and inflaming Midwestern populism in the early 20th century, splitting political parties in the process. If Trump continues his protectionist course, it could happen again.