The Wilmot Proviso was a proposed amendment to a military appropriations bill in 1846 that would have banned slavery in any territory acquired by the United States as a result of the Mexican-American War. David Wilmot, a Democratic congressman from Pennsylvania, wanted to keep slavery out of these territories because he believed that it was morally wrong and that it would give slaveholders too much power in the government. He also believed that free labor was more economically efficient than slave labor and that allowing slavery in the new territories would harm the interests of white laborers. The Wilmot Proviso was not passed by Congress, but it helped to fuel the debate over slavery that led to the Civil War.