Slavery in New Territories and Attempts at Compromise (College Board AP® US History)

Study Guide

Barbara Keese

Written by: Barbara Keese

Reviewed by: Bridgette Barrett

Updated on

Summary

Between the 1840s and the Civil War, the United States expanded its territories in the West. Conflict and attempts at compromise continued over the issue of slavery. Regional differences affected federal policies following the Mexican–American War. This period also saw the rise of a short-lived political party led by independent farmers who sought to have a greater voice in the admission of future states. Finally, people in the new territories looking forward to statehood pushed for popular sovereignty as they pursued their destiny. 

Mexican Cession Leads to Conflict & the Compromise of 1850

Wilmot Proviso (1846)

  • The Wilmot Proviso was a proposed amendment to a bill that prohibited slavery in any new territory acquired from Mexico

  • It failed to pass Congress because it failed to allow slavery in the territory once owned by Mexico

Southern Views

  • Many Southerners continued to support slavery

    • Southerners who supported slavery saw it as a constitutional right given by the Missouri Compromise

    • They wanted to extend the Missouri Compromise line to the Pacific Ocean to keep slavery in the new territories

    • They believed that the end of slavery would ruin their economy and way of life

Free Soil Movement 

  • The Free Soil Movement was a political party that included northern Democrats and Whigs

  • They believed that new territories should not allow slavery

    • They feared that the growth of slavery disadvantaged independent farmers and shifted political power in Congress

  • Popular sovereignty was the idea that the settlers of a new territory should vote to decide if slavery should be allowed within their borders

  • Senator Lewis Cass (Democrat from Michigan) popularized the concept in the late 1840s

    • He believed it was a democratic solution to address the issue of slavery

  • The idea attempted to balance the interests of pro-slavery and anti-slavery groups

  • Many believed that popular sovereignty would prevent the federal government from imposing a solution to the issue of slavery 

    • It was thought it would therefore reduce the risk of national conflict

  • Critics in the North argued that it opened the door for slavery to expand into areas previously closed under agreements like the Missouri Compromise

  • Pro-slavery groups saw popular sovereignty as an opportunity to use elections to secure slavery’s expansion

Henry Clay and the Compromise of 1850

  • Henry Clay (1777−1852) was a political leader who served as US senator, representative, and secretary of state

  • He introduced a series of laws to address regional tensions over slavery, resulting in the Compromise of 1850

Key points of the Compromise of 1850

  • Texas ceded territory to create today’s border for $10 million, paid to the US government

  • California joined the Union as a free state

    • This tipped the balance of power in favor of free states in the Senate, which upset Southern states

  • In New Mexico and Utah territories, popular sovereignty would determine slavery whether they allowed slavery 

  • Washington, DC, the site of the largest slave market in the United States, ended the sale of slaves, though slavery remained legal

  • The Fugitive Slave Law forced all US citizens to aid in the capture of runaway enslaved people, even if they reached a free state

    • This is one of the most controversial aspects of the Compromise of 1850

    • It imposed penalties on anyone who helped enslaved people escape

      • This law angered Northerners and abolitionists who saw it as a moral injustice

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Barbara Keese

Author: Barbara Keese

Expertise: History Content Creator

Barbara is an experienced educator with over 30 years teaching AP US History, AP Human Geography, and American History to grades 6–11 in Texas. She has developed teacher training, authored curricula, and reviewed textbooks to align with educational standards. Barbara has also served on Texas’ textbook adoption committee and the Round Rock History Preservation Commission, contributing to history education beyond the classroom. She holds a Master’s in Curriculum Development and certifications in History and Gifted/Talented Education. In her free time, she enjoys historical fiction and quilting blankets for veterans.

Bridgette Barrett

Author: Bridgette Barrett

Expertise: Geography Lead

After graduating with a degree in Geography, Bridgette completed a PGCE over 25 years ago. She later gained an MA Learning, Technology and Education from the University of Nottingham focussing on online learning. At a time when the study of geography has never been more important, Bridgette is passionate about creating content which supports students in achieving their potential in geography and builds their confidence.