The Crittenden Compromise was an unsuccessful proposal introduced by United States Senator John J. Crittenden (Constitutional Unionist of Kentucky) on December 18, 1860. It aimed to resolve the secession crisis of 1860–1861 by addressing the fears and grievances about slavery that led many slave-holding states to contemplate secession from the United States.
The compromise proposed six constitutional amendments and four Congressional resolutions. Crittenden introduced the package on December 18. It was tabled on December 31.
It guaranteed the permanent existence of slavery in the slave states and addressed Southern demands in regard to fugitive slaves and slavery in the District of Columbia. It proposed extending the Missouri Compromise line to the west, with slavery prohibited north of the 36° 30′ parallel and guaranteed south of it. The compromise included a clause that it could not be repealed or amended.
The compromise was popular among Southern members of the Senate, but it was generally unacceptable to the Republicans, who opposed the expansion of slavery beyond the states where it already existed into the territories. The opposition of their party's leader, President-elect Abraham Lincoln, was crucial. Republicans said the compromise "would amount to a perpetual covenant of war against every people, tribe, and state owning a foot of land between here and Tierra del Fuego." The only territories south of the line were parts of New Mexico Territory and Indian Territory. There was considerable agreement on both sides that slavery would never flourish in New Mexico. The South refused the House Republicans' proposal, approved by committee on December 29, to admit New Mexico as a state immediately. However, not all opponents of the Crittenden Compromise also opposed further territorial expansion of the United States. The New York Times referred to "the whole future growth of the Republic" and "all the Territory that can ever belong to the United States, — the whole of Mexico and Central America".