US History - Unit 3 - Antebellum Era

Louisiana Purchase

The 1803 land deal in which President Thomas Jefferson bought a huge territory from France, doubling the size of the United States and giving control of the Mississippi River.

Mexican-American War

A conflict (1846-1848) between the United States and Mexico, sparked by the annexation of Texas and border disputes. The U.S. won and gained large western territories.

Mexican Cession

The land Mexico gave to the United States in 1848 after the Mexican-American War (including present-day California, Nevada, Utah, and parts of several other states).

Kansas-Nebraska Act

The 1854 law that allowed settlers in Kansas and Nebraska to vote on whether to allow slavery ("popular sovereignty"), which led to violent conflict known as "Bleeding Kansas."

Caning Sumner

The 1856 incident when Southern Congressman Preston Brooks brutally attacked Northern Senator Charles Sumner with a cane on the Senate floor, symbolizing the growing tensions over slavery.

Dred Scott Decision

The 1857 Supreme Court ruling that said enslaved people were property, not citizens, and that Congress had no power to ban slavery in the territories—further dividing the nation.

John Brown

A radical abolitionist who believed in using violence to end slavery. He led attacks in "Bleeding Kansas" and organized the raid on Harpers Ferry in 1859.

Raid on Harpers Ferry

John Brown's failed 1859 attempt to seize a federal arsenal in Virginia to start a slave uprising. He was captured and executed, becoming a martyr in the North.

Compromise of 1850

A set of laws meant to ease tensions between free and slave states. It admitted California as a free state, allowed popular sovereignty in new territories, and included a stricter Fugitive Slave Act.

Bleeding Kansas

A series of violent clashes in the Kansas Territory (1854-1859) between pro-slavery and anti-slavery settlers after the Kansas-Nebraska Act allowed popular sovereignty. The conflict showed how deeply divided the nation had become over slavery.