WILMOT PROVISO. Immediately after the beginning of the Mexican-
American War (1846–1848), President James Polk asked Congress for $2
million, which he intended to use to buy a peace treaty with Mexico. A rider
was attached to the bill on 8 August 1846, by David Wilmot, a little-known
Democratic representative from Pennsylvania. The Wilmot Proviso, as it
became known, would forbid the extension of slavery to any territory
acquired from Mexico. The proviso caused a split among the Democrats as
northerners supported it and southerners opposed it. Polk eventually got
his appropriation, but Congress rejected the Wilmot Proviso after a bitter
debate. The provision was reintroduced several times afterward, but never
The implications of the Wilmot Proviso were far reaching. Wilmot's action
was on behalf of a group of northern Democrats who were angry over
Polk's political appointments, his apparent proslavery actions in Texas, his
compromise with Great Britain over the Oregon issue, and Polk's veto of a
rivers and harbors bill supported by midwestern Democrats. Many
northern Democrats were also resentful of the domination of the party by
southerners, feeling they had made too many concessions to the southern
wing in the past, and that the war with Mexico was an act of aggression
designed to expand slavery. As a result, the Wilmot Proviso sparked what
would become a rancorous national debate on the question of expanding
slavery into the territories.
All but one northern state legislature endorsed the Wilmot Proviso, while
southern legislatures expressed their determination to resist it. Southern
slaveholders resented the proviso as it seemed to stigmatize them,
suggesting that they were not the equals of northerners. More importantly,
southerners feared that if slavery could not expand, the slave system
would slowly be strangled once it was surrounded by free territories.
Prominent senator John C. Calhoun of South Carolina argued that the
territories were the common property of all the states, and Congress lacked
the power to prevent persons from taking their property into a territory;
therefore slavery was legal in all the territories. Failure to uphold this
principle, Calhoun declared, would destroy the balance between the free
and slave states. At the end of 1847, Michigan's Democratic senator Lewis
Cass argued for what would become known as "
popular sovereignty" by
proposing that the territories decide the slavery question themselves. This
idea attracted support from both northern and southern Democrats, each
of whom interpreted the concept to fit their own views about the expansion
of slavery.
Polk seems not to have understood the nature of the debate, holding that
the slavery issue was a domestic problem and not a question of foreign
policy. The president failed to recognize the question was, indeed, a major
foreign policy issue. Expansion had been a significant aspect of American
foreign policy since colonial days. The end of the Mexican-American War
would leave either slave owners or anti-slave forces in control of an
enormous amount of new territory; in time, the winner could control the
government. Polk thought that Congress was raising the issue in order to
embarrass him; he felt slavery could not exist in the poor soil conditions of
northern Mexico.
The proviso served to heighten sectional animosity, and later efforts to
pass the measure only provoked further debate. The modern Republican
Party would be founded on the principle of halting slavery's expansion,
and Abraham Lincoln would be elected to the presidency on a platform that
promised to carry out the principles of the Wilmot Proviso.