| Term | Definition |
| Nebraska Territory | Territory created in 1854 as a result of the Kansas-Nebraska Act, part of it became the state of Nebraska. |
| Kansas Territory | Territory created in 1854 by the Kansas-Nebraska Act; part of it became the state of Kansas. |
| Harpers Ferry | Town in Northeastern West Virginia, site of federal arsenal raided be abolitionist John Brown in 1859. |
| John C. Calhoun | U.S. Senator from South Carolina who believed in states' rights. |
| Henry Clay | U.S. Senator who was nicknamed "The Great Compromiser" for organizing important agreements such as the Missouri Compromise in 1820 and the Compromise of 1850. |
| Daniel Webster | Senator from the Massachusetts and opponent of slavery who supported the Compromise of 1850. |
| Stephen Douglas | U.S. Senator from Illinois who helped create the Kansas-Nebraska Act. |
| Harriet Beecher Stowe | Author of "Uncle Tom's Cabin," a novel that described the cruelties of slavery and which sold over 300,000 copies. |
| Dred Scott | Enslaved African American who claimed he was free because he had lived in a free state. His case reached the Supreme Court, which decided against him. |
| John Brown | Abolitionist who let attacks on supporters of slavery in Kansas and led a raid on Harpers Ferry, Virginia, in 1859. |
| Abraham Lincoln | 16th President of the U.S., from 1861 to 1865, who led the U.S. during the Civil War and was assassinated in 1865. |
| free state | state in which slavery was not allowed. |
| slave state | state in which slavery was allowed before the Civil War. |
| states' rights | Idea that states have the right to make decisions about issues that concern them. |
| Missouri Compromise | Law passed in 1820 that divided the Louisiana Territory into a southern area that allowed slavery and a northern area that did not. |
| Fugitive Slave Law | Law passed in 1850 that said escaped slaves had to be returned to their owners even if they reached free states. |
| Compromise of 1850 | Law under which California was admitted to the Union as a free state and the Fugitive Slave Law was passed. |
| Kansas-Nebraska Act | Law passed in 1854 allowing the people of these two territories to decide for themselves whether to allow slavery. |