Congress labored over the next three years to bolster the 1820 compromise. Thanks to abolitionists such as Garrison and Douglass, most Northerners were no longer willing to allow slavery to extend into any new territory, whether it lay above or below the line drawn by the Missouri Compromise. To break the dangerous stalemate, Senator Lewis Cass of Michigan advanced the doctrine of “popular sovereignty,” proposing that new territories would be organized without any mention of slavery one way or the other. When the territory wrote its own constitution and applied for admission as a state, the people of the territory would vote to be slave or free. As to California, it would be admitted to the Union directly instead of going through an interim of territorial status.
Southerners cringed. They assumed that California would vote itself free, as would New Mexico down the line. Senators Henry Clay and Daniel Webster worked out a new compromise. California would indeed be admitted to the Union as a free state. The other territories acquired as a result of the Mexican War would be subject to “popular sovereignty.” In addition, the slave trade in the District of Columbia would be discontinued. To appease the South, however, a strong Fugitive Slave Law was passed, strictly forbidding Northerners to grant: refuge to escaped slaves. Finally, the federal government agreed to assume debts Texas (admitted as a slave state in 1845) incurred before it was annexed to the United States.
As with the Missouri Compromise, the Compromise of 1850 pleased no one completely. Abolitionists were outraged by the Fugitive Slave Law, while states’ rights supporters saw the slave-free balance in Congress as shifting inexorably northward.