About Unit 8

💭 Essential Question: How did the interplay of territorial expansion, regional differences, and political ideologies fuel the sectional crisis?

Unit 8: Sectional Tensions (1820-1860) examines how the expansion of U.S. territory in the mid-19th century deepened conflicts over slavery, identity, and political power. The unit begins by exploring the ideas behind Manifest Destiny and how westward migration catalyzed significant changes, spurring both new opportunities and continued oppression. Next, students analyze how the Mexican-American War transformed the physical and political landscape of the nation. Students investigate the Mexican Cession and its consequences—particularly how new land reignited debates over slavery and disrupted the balance between North and South. Through the lens of compromise, conflict, and ideology, students explore how sectional differences grew sharper in the 1850s and how events like the Fugitive Slave Act, Bleeding Kansas, and the Dred Scott decision pushed the country toward civil war. The unit ends with an Annotated Source Collection, where students evaluate a variety of sources from the period to explain how expansion and disagreement over slavery fractured the nation.