Clown sightings in America increased in 2016, coinciding with periods when Donald Trump's chances of winning the presidency rose in polls. When Trump's chances decreased, reported clown incidents also stabilized. The data suggests that cultural anxiety over the election, rather than an actual threat from clowns, was behind the mass hysteria. Previous mass hysteria events, like reports of a "phantom slasher" in 1950s Taiwan during a period of uncertainty over war, demonstrate how uncertainty and fear can cause delusional mass behavior.