Final answer:
The Wilmot Proviso was favored by the North, as it represented an attempt to prevent the expansion of slavery into territories acquired from Mexico and to protect free labor. It passed in the House with northern support but failed in the Senate due to opposition from Southerners, contributing to the sectional crisis before the Civil War.
Step-by-step explanation:
The area of the country that favored the Wilmot Proviso was largely the North. This proviso, introduced by Democrat David Wilmot in 1846, proposed to ban slavery and involuntary servitude in territory acquired from Mexico. It gained widespread support in the North, reflecting the region's growing opposition to the expansion of slavery into new territories. Northerners viewed the Wilmot Proviso as a way to protect the interests of free workers, ensuring that they would not have to compete with slave labor in the territories. Although it passed the House of Representatives, it repeatedly failed in the Senate, where Southerners voted against it, perceiving it as a threat to slavery and their political power.
By the mid-1850s, tensions between the North and the South had intensified. The Wilmot Proviso had highlighted the sectional divide, contributing to the growing rift that would eventually lead to the American Civil War. While Southerners saw the proviso as an attack on their way of life and a potential limit to their ability to dominate national politics, it became a recurring point of contention in the larger national debate over slavery and states' rights.