Before the adoption of the Seventeenth Amendment to the U.S. Constitution in 1913, state legislatures elected U.S. senators. Candidates did not normally conduct a statewide campaign for the office. The times were not normal in 1858, however, when the Republicans in Illinois nominated Abraham Lincoln as their candidate for the senate seat held by Stephen Douglas. Lincoln, who had served only one term in Congress and had failed in his bid for the Senate in 1856, had nothing to lose by debating Douglas.

Speeches by the candidates and their seven debates attracted tens of thousands of listeners and received wide newspaper coverage. The debates started after Lincoln's "House Divided" speech in Springfield on June 16, 1858, at the Republican meeting endorsing him for the Senate. In that speech, Lincoln stated that the expansion of slavery into new territories had divided the nation. He used a quotation from the Bible...