How did the Kansas-Nebraska Act change American politics?
The Kansas-Nebraska Act thus brought about a fundamental shift in U.S. politics. It ended the second version of the two-party system, which had pitted Whigs against Democrats. It led to the creation of the third version of the two-party system, featuring the Democrats and Republicans as the dominant political parties in which formed along sectional lines and worsened tensions between the North and the South by turning every national election into a contest between sections instead of just a contest between parties.
