1846
Congressman David Wilmot introduced a proviso to ban slavery from all territory acquired from Mexico in the Mexican-American War. The House passed it twice; the Senate killed it. The Wilmot Proviso's failure — and the Senate's consistent blocking of any restriction on slavery's expansion — demonstrated the extent of slaveholder political power. The debate fractured both parties along sectional lines and foreshadowed the collapse of the Second Party System. The Mexican Cession ultimately added California, New Mexico, Arizona, Nevada, Utah, and Colorado — all contested territory for slavery.
Representative David Wilmot of Pennsylvania proposes an amendment in August 1846 barring slavery from any territory acquired from Mexico. The Proviso passes the House twice but is blocked by the Southern-controlled Senate. Though it never becomes law, it electrifies the slavery debate, reveals a Northern antislavery majority in the House, and foreshadows the sectional crisis.
Zoom in — months
Key events
- January 1846Wilmot Proviso Attempts to Ban Slavery in Mexican Cession
Representative David Wilmot of Pennsylvania proposes an amendment in August 1846 barring slavery from any territory acquired from Mexico. The Proviso passes the House twice but is blocked by the Southern-controlled Senate. Though it never becomes law, it electrifies the slavery debate, reveals a Northern antislavery majority in the House, and foreshadows the sectional crisis.
- August 8, 1846Wilmot Proviso Defeated: Congress Refuses to Limit Slavery in Mexican Cession
Congressman David Wilmot introduced a proviso to ban slavery from all territory acquired from Mexico in the Mexican-American War. The House passed it twice; the Senate killed it. The Wilmot Proviso's failure — and the Senate's consistent blocking of any restriction on slavery's expansion — demonstrated the extent of slaveholder political power. The debate fractured both parties along sectional lines and foreshadowed the collapse of the Second Party System. The Mexican Cession ultimately added California, New Mexico, Arizona, Nevada, Utah, and Colorado — all contested territory for slavery.