Early on in the Mexican-American War, America gained control over a vast swath of new territory extending from the Great Plains to the Pacific Ocean. In 1846, Congressman David Wilmot proposed a ban on slavery across the region, angering those who advocated on behalf of slavery’s westward expansion.
August 8, 1846
Provided, That, as an express and fundamental condition to the acquisition of any territory from the Republic of Mexico by the United States, by virtue of any treaty which may be negotiated between them, and to the use by the Executive of the moneys herein appropriated, neither slavery nor involuntary servitude shall ever exist in any part of said territory, except for crime, whereof the party shall first be duly convicted.
David Wilmot, “The Wilmot Proviso,” August 8, 1846, in Thomas Hart Benton, ed., Abridgment of the Debates of Congress, from 1789 to 1856, Vol. 15 (New York: D. Appleton & Co., 1861), 646.
Reprinted from The U.S. Constitution, A Reader, Published by Hillsdale College