, 1820, Maine was made a state and Missouri was authorized to adopt a constitution having no restrictions on slavery.
Settlement of Missouri itself quickened, spreading in the 1820s over the river valleys into central Missouri and by the 1830s into W Missouri. The boundaries of the state were formed after Native Americans gave up their claim to Platte co. in 1836; this strip of land in the northwest corner of Missouri was added to the state. Mormon immigrants came to settle Missouri in the 1830s, but their opposition to slavery and their growing numbers made them unwelcome and they were driven from the state in 1839. Slaveholding interests became politically powerful, but the state remained principally a fur-trading center. In 1854 the problem of slavery was made acute with the passage of the Kansas-Nebraska Act, leaving the question of slavery in the Kansas and Nebraska territories to the settlers themselves. The proslavery forces in Missouri became very active in trying to win Kansas for the slave cause and contributed to the violence and disorder that tore the territory apart in the years just prior to the Civil War.
Kansas-Nebraska Act, bill that became law on May 30, 1854, by which the U.S. Congress established the territories of Kansas and Nebraska. By 1854 the organization of the vast Platte and Kansas river countries W of Iowa and Missouri was overdue. As an isolated issue territorial organization of this area was no problem. It was, however, irrevocably bound to the bitter sectional controversy over the extension of slavery into the territories and was further complicated by conflict over the location of the projected transcontinental railroad. Under no circumstances did proslavery Congressmen want a free territory (Kansas) W of Missouri. Because the West was expanding rapidly, territorial organization, despite these difficulties, could no longer be postponed. Four attempts to organize a single territory for this area had already been defeated in Congress, largely because of Southern opposition to the Missouri Compromise.
