6.1The act that broke the parties

In 1854, Senator Stephen Douglas pushed through the Kansas-Nebraska Act, which allowed settlers in those territories to decide for themselves whether to permit slavery. This repealed the Missouri Compromise line that had kept slavery out of northern territories for a generation, and it enraged the North.

The act detonated the party system. The Whigs, split hopelessly between North and South, disintegrated. In the ensuing chaos, anti-slavery Whigs, disaffected Democrats, and members of the small Free Soil movement began forming a new organization dedicated to stopping slavery's expansion. Within two years it had a name—the Republican Party—and startling momentum across the North.