APUSH Period 5 — From Manifest Destiny to Secession, 1844–1861

Period 5 of AP United States History runs from 1844 to 1877 and carries between 10 and 17 percent of the exam. This material covers its first half: the seventeen years in which westward expansion turned the question of slavery in the territories into a crisis that no compromise could settle.

You start with expansion itself: the idea of Manifest Destiny and the annexation of Texas, the Oregon settlement at the 49th parallel, President Polk's case for war with Mexico and the critics who asked on whose soil American blood had been shed, and the Treaty of Guadalupe Hidalgo, including what it promised the Mexicans who suddenly lived inside the United States and how far those promises were kept. The California gold rush shows how quickly migration from the East, Latin America and China reshaped the West, and how quickly it produced conflict.

The second half follows the collapse of compromise step by step: the Compromise of 1850 and the Fugitive Slave Act that drew Northerners into enforcing slavery; the Kansas-Nebraska Act and the repeal of the Missouri Compromise line; Bleeding Kansas and the Lecompton Constitution that split the Democratic Party; the Dred Scott decision; the Lincoln-Douglas debates and the Freeport Doctrine; John Brown's raid on Harpers Ferry; the four-way election of 1860; and the secession of seven Lower South states before Lincoln took office, after the Crittenden Compromise failed.

The quiz has twelve questions. Most are built the way the exam builds them, around a short primary source quoted in the question: John L. O'Sullivan on manifest destiny, Polk's war message, Chief Justice Taney's opinion, Lincoln's House Divided speech, John Brown's last note and South Carolina's declaration of the causes of secession. You are asked about the situation a source came from, the position it answered or the development it reflects, not just to recall a name or a date. Wrong options are the confusions students actually make, such as the Crittenden plan mistaken for the Kansas-Nebraska Act, or Douglas placed in the Lower South in 1860.

The seventeen flashcards fix the laws, cases, treaties and events of the period with their dates and their significance, from the Oregon Treaty to the founding of the Confederacy in February 1861.

Use the material while you study Unit 5 in class, or in the spring as review before the May exam. The companion material on the Civil War and Reconstruction completes the period.

• Explain how Manifest Destiny, Texas annexation and the Mexican-American War enlarged the United States and reopened the question of slavery in the territories
• Describe the terms of the Treaty of Guadalupe Hidalgo and the experience of Mexican residents and gold-rush migrants in the West
• Trace the failure of compromise from 1850 to 1861, from the Fugitive Slave Act to Kansas-Nebraska, Lecompton and Dred Scott
• Explain how the 1860 election and the secession of the Lower South followed from the sectional party system
• Use a short primary source to identify its historical situation and the position it answers

Practice material written by Zestly, based on the College Board AP U.S. History course framework (course and exam description effective fall 2026), Unit 5, Period 5: 1844–1877, topics on Manifest Destiny, the Mexican–American War, the Compromise of 1850, sectional conflict and the election of 1860. Quoted sources are public-domain US documents and writings of 1845–1860.