The 1850 New Mexico crisis occurred when Texas governor Peter H. Bell threatened to dispatch his state militia to the New Mexico Territory to enforce Texas' claim to Santa Fe and the state east of the Rio Grande in the aftermath of the territory's adoption of a "free state" constitution. The crisis was resolved by the Compromise of 1850, under which California would be admitted as a free state while New Mexico remained a territory.
The United States' acquisition of the "Mexican Cession" at the end of the Mexican-American War in 1848 reignited the slavery debate as Southern leaders advocated for the opening of these new territories to slaveholders and anti-extensionists and abolitionists in the North opposed the spread of slavery. Texas organized Santa Fe County on the war's end, but citizens of New Mexico - which had a very small English-speaking population - petitioned the federal government to organize them into a federal territory. After the people of New Mexico turned away the Texan agent Robert Neighbors as he attempted to organize counties in New Mexico as part of Texas, a public outcry ensued in June 1850. Many Texans called for military intervention or secession, and Governor Bell called a special session of the Texas legislature. Before the session could begin, the settlers of New Mexico ratified a constitution which outlawed slavery and pressedd territorial claims overlapping with Texas'. The Governor threatened to dispatch the state militia to resolve the issue, and Whig politician Alexander H. Stephens warned of the republic's doom if the "Rubicon" of the Rio Grande was crossed. After the death of the anti-extentionist President Zachary Taylor, his successor Millard Fillmore shelved New Mexico's statehood application, while the Compromise of 1850 would admit California to the union while ignoring New Mexico. A Senate committee offered Texas $10 million to give up any claims to New Mexican territory, and the Boundary Act of 1850 was signed by Fillmore in late summer and by the Texas state legislature on 25 November 1850. New Mexico would go on to adopt a pro-slavery constitution in 1859, although the territory never became home to a single slave.