The Missouri Compromise was an agreement passed in 1820 between the pro-slavery and anti-slavery factions in the United States Congress, involving primarily the regulation of slavery in the western territories. It prohibited slavery in the former Louisiana Territory north of the parallel 36°30' north except within the boundaries of the proposed state of Missouri. Prior to the agreement, the House of Representatives had refused to accept this compromise and a conference committee was appointed. The United States Senate refused to concur in the amendment, and the whole measure was lost.
During the following session (1819-1820), the House passed a similar bill with an amendment, introduced on January 26, 1820 by John W. Taylor of New York, allowing Missouri into the union as a slave state. The question had been complicated by the admission in December of Alabama, a slave state, making the number of slave and free states equal. In addition, there was a bill in passage through the House (January 3, 1820) to admit Maine as a free state.
The Senate decided to connect the two measures. It passed a bill for the admission of Maine with an amendment enabling the people of Missouri to form a state constitution. Before the bill was returned to the House, a second amendment was adopted on the motion of Jesse B. Thomas of Illinois, excluding slavery from the Missouri Territory north of the parallel 36°30' north (the southern boundary of Missouri), except within the limits of the proposed state of Missouri.
