Dred Scott v. Sandford
Courtesy of the Library of Congress
The United States saw a great expansion westward at the turn of the nineteenth century. When the Missouri Territory petitioned Congress for statehood in 1820, the question of whether slavery would be legal in the new states came to a head. In order to keep a balance between slave states and non-slave states, it was decided that Missouri would enter as a slave state while Maine would enter as a non-slave state. It was also decided that a border would be drawn across the country at the 36° 30' latitude line—all territories north of the boundary would enter as free states, all territories south would enter as slave states. New states would enter the country in pairs to preserve the precarious balance between locations allowing and outlawing slavery.