A little after the Manifest Destiny, the U.S. faced a series of troubles of sectional balances over whether or not the land acquired should be free or slavery states. The Compromise of 1850, proposed by Senator Henry Clay, included measures that dealt with the land acquired specifically from the Mexican War.
Until 1845, it had seemed likely that slavery would be confined to the areas where it already existed. It had been given limits by the Missouri Compromise in 1820 and had no opportunity to overstep them. The new territories made renewed expansion of slavery a real likelihood.
Many Northerners believed that if not allowed to spread, slavery would ultimately decline and die. To justify their opposition to adding new slave states, they pointed to the statements of Washington and Jefferson, and to the Ordinance of 1787, which forbade the extension of slavery into the Northwest. Texas, which already permitted slavery, naturally entered the Union as a slave state. But California, New Mexico and Utah did not have slavery, and when the United States prepared to take over these areas in 1846, there were conflicting suggestions on what to do with them.
Extremists in the South urged that all the lands acquired from Mexico be thrown open to slave holders. Antislavery Northerners, on the other hand, demanded that all the new regions be closed to slavery. One group of moderates suggested that the Missouri Compromise line be extended to the Pacific with free states north of it and slave states to the south. Another group proposed that the question be left to "popular sovereignty," that is, the government should permit settlers to enter the new territory with or without slaves as they pleased and, when the time came to organize the region into states, the people themselves should determine the question.
Southern opinion held that all the territories had the right to sanction slavery. The North asserted that no territories had the right. In