Presidential debates in the United States were inspired by a famous Illinois senatorial debate in 1858 between Abraham Lincoln and incumbent Stephen Douglas that was held without a moderator or panel. As Douglas campaigned around Illinois, Lincoln attended his opponent’s campaign speeches and heckled Douglas from the crowd. Lincoln’s antics drummed up sufficient attention, and finally he and Douglass met for a three-hour debate during which the men discussed slavery and various conspiracy theories.
Douglas won the Senate seat, and Lincoln didn’t participate in any debates in 1860 during his run for president. Nevertheless, the men’s debate set a stage for the use of debates in future election cycles. The 2016 debates between Donald Trump and Hillary Clinton were likened by many historians to the Lincoln-Douglas debate of 1858.