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Timeline of Compromises over Slavery

From the nation's very inception, the existence of slavery stood in glaring contrast to the ideals of liberty and justice expressed in the preamble to the Constitution. The Constitution itself protected the institution of slavery (while never actually using the word slave) through a number of compromises worked out between pro-slavery and anti-slavery factions. These constitutional compromises did not resolve the conflict, however, and Congress passed other compromises in an effort to prevent the young nation from breaking apart.

“We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defense, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.”

—Preamble to the United States Constitution

The Constitution

The “Three-Fifths Compromise” provided a formula for calculating a state’s population, in which three-fifths of “all other persons” (i.e., slaves) would be counted for purposes of representation and taxation. The Constitution also included a provision to ban the importation of slaves starting in 1808, and a fugitive slave clause requiring escaped slaves to be returned to their owners.

Fugitive Slave Act (1793)

Required that escaped slaves found in free states be caught and returned to their masters. The Act also denied freed slaves the right to a jury trial and other constitutional rights.

Missouri Compromise (1820)

Banned slavery in the Louisiana Territory north of the 36° 30’ parallel, except within the borders of the state of Missouri, which would be admitted as a slave state; Maine to be admitted as a free state.

Second Missouri Compromise (1821)

Missouri was admitted as a state despite a provision in its constitution excluding “free negroes and mulattoes” from the state.

“Gag rule” in Congress (1831-1844)

When abolitionists began submitting petitions about ending slavery to Congress, proslavery representatives passed a "gag rule" that prevented those petitions from being discussed.

Compromise of 1850

Necessary to determine whether slavery would be allowed in states created by the territory acquired from Mexico in the Mexican-American War. California was admitted as a free state, while the Territory of New Mexico (including present-day Arizona and part of Nevada) allowed slavery. The Compromise also included a measure banning the slave trade (but not slavery itself) within the District of Columbia, as well as a new and more forceful Fugitive Slave Law.

Kansas-Nebraska Act (1854)

Created the territories of Kansas and Nebraska and provided that residents of those territories would vote to determine whether the two territories would allow slavery. This resulted in violence between pro-slavery and anti-slavery advocates who moved to the territories.

Crittenden Compromise (1860)

An unsuccessful attempt by Senator John J. Crittenden of Kentucky to resolve the secession crisis by making concessions to slave states. Crittenden proposed a constitutional amendment to guarantee the permanent existence of slavery in the slave states along the boundaries established by the Missouri Compromise line.

Source | American Social History Project/Center for Media and Learning, 2009.
Creator | American Social History Project/Center for Media and Learning
Rights | Copyright American Social History Project/Center for Media and Learning Creative Commons LicenseThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Item Type | Timeline
Cite This document | American Social History Project/Center for Media and Learning, “Timeline of Compromises over Slavery,” SHEC: Resources for Teachers, accessed November 28, 2023,

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