In terms of their impact on the Transcendentalists, exploration and settlement were significant primarily in relation to slavery. As the possibility of statehood arose for a territory, the question of whether it would be a slave state or a free state became an issue that drew national attention and heated debate.
In 1819, Missouri requested admission to the Union as a slave state. The country at the time contained an equal number of slave and free states (twenty-two total — eleven free and eleven slave). Congress hammered out the Missouri Compromise of 1820 in order to preserve this balance and to prevent further rancor and division between slavery and antislavery interests. Under the Missouri Compromise, Missouri was admitted as a slave state, Maine was admitted as a free state, and slavery was prohibited in the rest of the Louisiana Purchase north of the southern boundary of Missouri. This arrangement satisfied neither the South, which resented any attempt by the federal government to control slavery, nor the North, which was angered by government complicity in expanding slave territory.
Texas, spurred on by defeat at the Alamo, won its freedom from Mexico in 1836. Its annexation to the United States in 1845 was opposed by antislavery forces because of the likelihood that it would become a slave state and because it also made war with Mexico, which had refused to recognize the independence of Texas, impossible to avoid. War was declared in 1846, further polarizing the nation. Southerners supported the war, Northerners opposed it. At the war's end in 1848, Mexico recognized Texas as part of the United States and surrendered additional territory (California, Nevada, and Utah, most of New Mexico and Arizona, parts of Colorado and Wyoming).
