Introduced by Representative David Wilmot of Pennsylvania in the United States Congress in August 1846, the proviso stated that, as a condition to the United States acquiring territory from Mexico, "neither slavery nor involuntary servitude" could exist in any part of that territory. The proviso served as a lightning rod to the Congressional debates over slavery which dominated the national agenda from 1846 until the 1850 Compromise, intensifying divisions between North and South and giving rise to the free-soil movement which would find institutional form in 1848 in the Free Soil party and, in 1854, in the Republican party. Walt Whitman's editorial support of the Wilmot Proviso throughout the late 1840s positioned him solidly within the Free Soil camp and showed his thinking on slavery to be motivated more by concern for white labor than by sympathy for slaves, a position he consistently held in his journalism up through the Civil War.
Disputes over slavery had supposedly been settled by compromises in the United States Constitution and agreements such as the 1820 Missouri Compromise, and the abolitionists of the 1830s and 1840s had proved ineffective in moving Congress to reconsider the issue. But with a vast new territory including California, New Mexico, and Texas opened up by United States victory in its war with Mexico, the debate over slavery exploded. Northerners who came to be known as Free-Soilers promoted the Wilmot Proviso as a means by which free (i.e., white) labor could enter the new territories without having to compete with—and, thus, be "degraded" by—slave labor. Southerners vigorously opposed the Wilmot Proviso, fearing that additional free states would decisively tip the balance of power to the North. The House passed the Wilmot Proviso along sectional lines in both 1846 and 1847, but the Senate, in which the South had greater power, blocked the proviso in March of 1847.
Despite the proviso's defeat, debate over the bill gave rise to the free-soil movement which Whitman would promote in Brooklyn Eagle editorials from December 1846 until his departure in January 1848. Whitman's editorials largely echo the Free-Soilers' position that the introduction of slavery would discourage, if not prohibit, white laborers from migrating to the new territories. Whitman's distinction between abolitionist "interference" with slavery in the South and the question of the extension of slavery into the West invokes the memory of Thomas Jefferson as the prototypical Free-Soiler and characterizes the debate as an issue not of race but of class between white labor and the aristocracy of the South. While Whitman's position follows the Free-Soilers' emphasis on white labor and not on moral opposition to slavery, Whitman, unlike many Free-Soilers, does not evoke white anxiety about associating with blacks as a reason to support the proviso.
Debate over the Wilmot Proviso divided both the Whig and Democratic parties, whose dissenters merged to form the Free Soil party in 1848. While the proviso became largely irrelevant with passage of the 1850 Compromise, it ignited and intensified the divisions between North and South that led to Civil War.
Bibliography
Allen, Gay Wilson. The Solitary Singer: A Critical Biography of Walt Whitman. 1955. Rev. ed. 1967. Chicago: U of Chicago P, 1985.
Klammer, Martin. Whitman, Slavery, and the Emergence of "Leaves of Grass." University Park: Pennsylvania State UP, 1995.
McPherson, James M. Battle Cry of Freedom: The Civil War Era. New York: Oxford UP, 1988.
Rubin, Joseph Jay. The Historic Whitman. University Park: Pennsylvania State UP, 1973.
Whitman, Walt. The Gathering of the Forces. Ed. Cleveland Rodgers and John Black. 2 vols. New York: Putnam, 1920.