In 1858 the Illinois State Legislature elected the state's Senator. Thus the results of that year's legislative elections largely determined the outcome of the renowned contest between Abraham Lincoln and Stephen Douglas. This map shows how the state of Illinois split along largely sectional lines in the returns of 1858. The Democrat Douglas carried the state's southern and west-central regions, while the Republican Lincoln prevailed in east-central Illinois and the state's staunchly anti-slavery northern tier. Note that in several districts of central Illinois state senators cast their votes for Douglas while house members representing the same district supported Lincoln. Springfield's state senator supported Lincoln, while its representative backed Douglas. Southeastern Illinois' St. Clair County also split its support in this election.

For more information about politics in the 19th century, please look at Lincoln/Net's Getting the Message Out! National Political Campaign Materials, 1840-1860 Web site.