James Polk elected president

Texas admitted into Union

United States declares war on Mexico

Treaty with Britain divides Oregon Country

Wilmot Proviso approved by House but not by Senate

American troops capture Mexico City

Gold found in California

Treaty of Guadalupe Hidalgo transfers Mexican lands to United States

Free-Soil Party forms

President Taylor dies

Millard Fillmore assumes presidency

Compromise of 1850 preserves Union

Northern abolitionists reject Fugitive Slave Act

American (Know-Nothing) Party forms

Harriet Beecher Stowe publishes Uncle Tom’s Cabin

Ostend Manifesto urges seizure of Cuba

Kansas-Nebraska Act tests policy of popular sovereignty

Republican Party forms

Turmoil in Kansas undermines popular sovereignty

James Buchanan elected president

Dred Scott v. Sandford allows slavery in U.S. territories

President Buchanan urges Congress to admit Kansas under the proslavery Lecompton constitution and seeks to buy and annex Cuba as a slave state

Abraham Lincoln debates Stephen Douglas for U.S. Senate seat

John Brown raids federal arsenal at Harpers Ferry

Abraham Lincoln elected president in four-way contest