One of the most momentous political reorganizations in United States history took place in the 1850s. That reorganization created the Republican Party, which still exists, and dangerously polarized the nation. This module has two parts. The first depicts the event that precipitated the reorganization: The Kansas-Nebraska Act of 1854. That law so outraged many Northern voters that they abandoned their old party affiliations to join the newly formed Republican party, whose principal issue was opposition to the Kansas-Nebraska Act and all that the act seemed to imply. The second map in this module tracks Congressional Elections from 1852 to 1860. In dramatic fashion, it reveals the rise of the Republican Party after 1854 and the clear division of the nation by 1860 between a predominantly Republican North and a predominantly Democratic South.

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