Slavery was not a new topic for discussion during the middle 1800's in the United States. After the Mexican American War, the annexation of new territory led to an important crisis. Will there be new states added to the Union? If so, would they be free states or slaveholding states?.
The annexation of Texas to the United States and the gain of new territory by the Treaty of Guadalupe Hidalgo at the close of the Mexican War (1848) aggravated the hostility between North and South concerning the question of slavery. The free states favored the proposal made in the Wilmot Proviso to exclude slavery from all the lands acquired from Mexico. This, naturally, met with violent Southern opposition. When California sought (1849) admittance to the Union as a free state, a serious crisis threatened. With a precarious balance of 14 free and 14 slave states in the Union, Southerners could not maintain their power in Washington, D.C., with the admission of another free state. Southerners increasingly talked of secession.
In January 1850 Senator Henry Clay of Kentucky tried to heal the breach with five actions packaged in one bill. California was to be admitted as a free state, but the territories of Utah and New Mexico, which were then largely ungoverned, were to be given governments with the authority to decide the issue of slavery themselves. Additionally, the Fugitive Slave Act of 1793 would be amended to include enforcement provisions against the North and a requirement that the citizens would help catch and return runaway slaves. To compensate the North for the fugitive slave amendments, the interstate trade of slaves would be banned in the District of Columbia - a largely symbolic gesture since slave trading would continue in Virginia and Maryland and the private sale of slaves would still be permissible in the capital. The bill also resolved boundary disputes between the government of Texas and the federal government.