What was the Wilmot Proviso (1846)?


The Wilmot Proviso was an unsuccessful 1846 proposal in the United States Congress to ban slavery in territory acquired from Mexico in the Mexican-American War. The conflict over the Wilmot Proviso was one of the major events leading to the American Civil War (1861-1865).




Both major political parties had laboured long to keep divisive slavery issues out of national politics. The Democrats had generally been successful in portraying those within their party attempting to push a purely sectional issue as extremists that were well outside the normal scope of traditional politics. However, midway through Polk’s term, Democratic dissatisfaction with the administration was growing within the Martin Van Buren, or Barnburner, wing of the Democratic Party over other issues. Many felt that Van Buren had been unfairly denied the party’s nomination in 1844 when southern delegates resurrected a convention rule, last used in 1832, requiring that the nominee had to receive two-thirds of the delegate votes. Many in the North were also upset with the Walker tariff which reduced the tariff rates; others were opposed to Polk’s veto of a popular river and harbour improvements bill, and still others were upset over the Oregon settlement with Great Britain where it appeared that Polk did not pursue the northern territory with the same vigour he used to acquire Texas. Polk was seen more and more as enforcing strict party loyalty primarily to serve southern interests.

The Whigs faced a different scenario. The victory of James K. Polk (Democrat) over Henry Clay (Whig) in the 1844 presidential election had caught the Southern Whigs by surprise. The key element of this defeat, which carried over into the congressional and local races in 1845 and 1846 throughout the South, was the party’s failure to take a strong stand favouring Texas annexation. Southern Whigs were reluctant to repeat their mistakes on Texas, but, at the same time, Whigs from both sections realised that victory and territorial acquisition would again bring out the issue of slavery and the territories. In the South in particular, there was already the realisation, or perhaps fear, that the old economic issues that had defined the Second Party System were already dead. Their political goal was to avoid any sectional debate over slavery which would expose the sectional divisions within the party.

Introduction and Debate on the Proviso


David Wilmot, a Democratic congressman from Pennsylvania, and a group of other Barnburner Democrats including Preston King and Timothy Jenkins of New York, Hannibal Hamlin of Maine, Gideon Welles of Connecticut, and Jacob Brinkerhoff of Ohio, had already been meeting in early August strategy meetings. Wilmot had a strong record of supporting the Polk Administration and was close to many Southerners. With the likelihood that Wilmot would have no trouble gaining the floor in the House debate, he was chosen to present the amendment to the appropriations bill that would carry his name. Wilmot offered the following to the House in language modelled after the Northwest Ordinance of 1787:


William W. Wick, Democrat of Indiana, attempted to eliminate total restriction of slavery by proposing an amendment that the Missouri Compromise line of latitude 36°30′ simply be extended west to the Pacific. This was voted down 89-54. The vote to add the proviso to the bill was then called, and it passed by 83-64. A last-ditch effort by southerners to table the entire bill was defeated by 94-78, and then the entire bill was approved 85-80. These votes fell overwhelmingly along sectional rather than party lines.


The issue resurfaced at the end of the year when Polk, in his annual message to Congress, renewed his request with the amount needed increasing to three million dollars. Polk argued that, while the original intent of the war had never been to acquire territory (a view hotly contested by his opponents), an honourable peace required territorial compensation to the United States. The Three Million Dollar Bill, as it was called, was the sole item of business in the House from 08 February until 15 February 1847. Preston King reintroduced the Wilmot Proviso, but this time the exclusion of slavery was expanded beyond merely the Mexican territory to include “any territory on the continent of America which shall hereafter be acquired”. This time Representative Stephen Douglas, Democrat of Illinois, reintroduced the proposal to simply extend the Missouri Compromise line to the west coast, and this was again defeated 109-82. The Three Million Dollar Bill with the proviso was then passed by the House 115-106. In the Senate, led by Thomas Hart Benton (Democrat), the bill was passed without the proviso. When the bill was returned to the House the Senate bill prevailed; every Northern Whig still supported the proviso, but 22 Northern Democrats voted with the South.

In 1848, the Treaty of Guadalupe Hidalgo ending the war was submitted to the Senate for approval. Douglas, now in the Senate, was among those who joined with the South to defeat an effort to attach the Wilmot Proviso to the treaty. In the prior year’s debate in the House, Douglas had argued that all of the debate over slavery in the territories was premature; the time to deal with that issue was when the territory was actually organised by Congress. Lewis Cass (Democrat) in December 1847, in his famous letter to A.O.P. Nicholson in Tennessee, further defined the concept of popular sovereignty which would soon evolve as the mainstream Democratic alternative to the Wilmot Proviso:


Aftermath and Legacy

With the approval of the treaty, the issue moved from one of abstraction to one involving practical matters. The nature of the Constitution, slavery, the value of free labour, political power, and ultimately political realignment were all involved in the debate. Historian Michael Morrison argues that from 1820 to 1846 a combination of “racism and veneration of the Union” had prevented a direct Northern attack on slavery. While the original Southern response to the Wilmot Proviso was measured, it soon became clear to the South that this long postponed attack on slavery had finally occurred. Rather than simply discuss the politics of the issue, historian William Freehling noted, “Most Southerners raged primarily because David Wilmot’s holier-than-thou stance was so insulting.”

In the North, the most immediate repercussions involved Martin Van Buren and the state of New York. The Barnburners were successfully opposed by their conservative opposition, the Hunkers, in their efforts to send a pro-proviso batch of delegates to the 1848 Democratic National Convention. The Barnburners held their own separate convention and sent their own slate of delegates to the convention in Baltimore. Both delegations were seated with the state’s total votes split between them. When the convention rejected a pro-proviso plank and selected Lewis Cass as the nominee, the Barnburners again bolted and were the nucleus of forming the Free Soil Party. Historian Leonard Richards writes of these disaffected Democrats:


Historian William Cooper presents the exactly opposite Southern perspective:


In Alabama, with no available candidate sufficiently opposed to the proviso, William L. Yancey secured the adoption by the state Democratic convention of the so-called “Alabama Platform”, which was endorsed by the legislatures of Alabama and Georgia and by Democratic state conventions in Florida and Virginia. The platform called for no federal restrictions of slavery in the territories, no restrictions on slavery by territorial governments until the point where they were drafting a state constitution in order to petition Congress for statehood, opposition to any candidates supporting either the proviso or popular sovereignty, and positive federal legislation overruling Mexican anti-slavery laws in the Mexican Cession. However, the same Democratic Convention that had refused to endorse the proviso also rejected incorporating the Yancey proposal into the national platform by a 216-36 vote. Unlike the Barnburner walkout, however, only Yancey and one other Alabama delegate left the convention. Yancey’s efforts to stir up a third party movement in the state failed.


The opening salvo in a new level of sectional conflict occurred on 13 December 1848, when John G. Palfrey (Whig) of Massachusetts introduced a bill to abolish slavery in the District of Columbia. Throughout 1849 in the South “the rhetoric of resistance to the North escalated and spread”. The potentially secessionist Nashville Convention was scheduled for June 1850. When President Taylor in his December 1849 message to Congress urged the admission of California as a free state, a state of crisis was further aggravated. Historian Allan Nevins sums up the situation which had been created by the Wilmot Proviso:



In regard to the territory the Proviso would have covered, California had a brief period of slavery due to slave owning settlers arriving during the 1848 California Gold Rush. Since there were no slave patrols or laws protecting slavery in the territory, slave escapes were quite common. Ultimately, California decided to ban slavery in their 1849 constitution and was admitted to the Union as a free state in 1850. Nevada would never have legal slavery and was admitted to the Union as a free state in 1864. The territories of Utah and New Mexico would have slavery from the time they were acquired by America in 1848 until July of 1862, when the United States banned slavery in all federal territories. However, Utah’s experience with slavery was minimal, as the 1860 census recorded only 30 slaves in the entire state.

Refer to American Civil War (1861-1865).


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