The antislavery declaration reflected the national political situation. The Democrats had divided over slavery and expansion during the 1844 election, but after his victory James K. Polk had pushed for the acquisition of the Oregon country and for a larger share of Texas from Mexico.
Northern Democrats such as Wilmot, who feared the addition of slave territory, had resented Polk’s willingness to compromise the Oregon dispute with Great Britain at the forty- ninth parallel-less territory than expected. More interested in northern free labor than in the plight of southern slaves, Wilmot had been an administration loyalist until he presented his proviso. Apparently, it may not even have been his idea. The language was taken from the Northwest Ordinance of 1787, and several antislavery congressmen had written similar measures.
Although the measure was blocked in the southern-dominated Senate, it helped widen the growing sectional rift, and it inspired such politicians of the time as James Buchanan, Lewis Cass, and John C. Calhoun to formulate their own plans for dealing with slavery as the nation expanded its territory.
The Reader’s Companion to American History. Eric Foner and John A. Garraty, Editors. Copyright © 1991 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.