The Lincoln–Douglas debates were a series of seven debates in 1858 between Abraham Lincoln, the Republican Party candidate for the United States Senate from Illinois, and incumbent Senator Stephen Douglas, the Democratic Party candidate. Until the Seventeenth Amendment to the United States Constitution, which provides that senators shall be elected by the people of their states, was ratified in 1913, senators were elected by their respective state legislatures. Therefore, Lincoln and Douglas were trying to win the people's votes for legislators in the Illinois General Assembly, aligned with their respective political parties.
The debates were designed to generate publicity—some of the first examples of what in modern parlance would be characterized as "media events". For Lincoln, they were an opportunity to raise both his state and national profile and that of the burgeoning Republican Party, newly organized four years before in Ripon, Wisconsin, in 1854. For Senator Douglas, they were an opportunity to defend his record—especially his role in promoting the doctrine of popular sovereignty in regard to the issue of American black slavery and its role in the passage of the Kansas–Nebraska Act of 1854. The candidates spoke in each of Illinois's nine congressional districts. They had already spoken in the state capital of Springfield and in the state's largest city of Chicago within a day of each other, so they decided that their future joint appearances would be held in the remaining seven congressional districts. Since Douglas was the incumbent, he had very little to gain from these debates. However, Lincoln, only a one-term U.S. Representative (congressman) a decade before, was gaining support, having spoken the day after Douglas spoke in Chicago, and thus presenting a rejoinder Douglas could not answer back with a rebuttal. Each debate lasted about three hours, with each candidate speaking for thirty minutes, followed by a ninety-minute response and a final thirty-minute rejoinder by the first candidate. As the incumbent, Douglas spoke first in four of the debates, and Douglas and Lincoln alternated who spoke first at the remaining debates. They were held outdoors, weather permitting, from about 2 to 5 p.m.