Compromise of 1850

In 1820, almost exactly 30 years before his Compromise of 1850 speech, Clay engineered the passage of the Missouri Compromise. In an already fraught political climate, in which tensions over slavery were high, the compromise had three main effects: Missouri entered the United States as a slave state; Maine entered as a free state; and slavery was prohibited in the rest of the Louisiana Purchase territory above the 36°30′parallel.

Achieving the Missouri Compromise was challenging. The Senate initially attempted to link the Maine and Missouri petitions for statehood, effectively ensuring that Missouri, a slave state, could not enter without free-soil Maine. With the addition of the 36°30′parallel compromise proviso, the linked bills passed the Senate—only to be defeated in the House by representatives still fighting for a free Missouri. Clay, with his pro-compromise allies, managed to push each component forward by dividing the bills once again and pressuring for compromise on each component individually.

The Missouri Compromise did not long outlive the Compromise of 1850, foreshadowing the deterioration of the latter. In 1854, with the Kansas-Nebraska Act, the Missouri Compromise was repealed. Only three years later, the Supreme Court ruled the Missouri Compromise to be unconstitutional in the Dred Scott decision, which stated that Congress lacked the authority to prohibit slavery in the territories.