Mexican Cession - Subsequent Organization and The North-South Conflict

Subsequent Organization and The North-South Conflict

Soon after the war started and long before negotiation of the new US-Mexico border, the question of slavery in the territories to be acquired polarized the Northern and Southern United States in the bitterest sectional conflict up to this time, which lasted for a deadlock of four years during which the Second Party System broke up, Mormon pioneers settled Utah, the California Gold Rush settled California, and New Mexico under a federal military U.S government turned back Texas's attempt to assert control over territory Texas claimed as far west as the Rio Grande. Eventually the Compromise of 1850 preserved the Union, but only for another decade. Proposals included:

• The Wilmot Proviso, which was created by Republican Party Senator David Wilmot, banning slavery in any new territory to be acquired from Mexico, not including Texas which had been annexed the previous year. Passed by the United States House of Representatives in August 1846 and February 1847 but not the Senate. Later an effort to attach the proviso to the Treaty of Guadalupe Hidalgo also failed.
• Failed amendments to the Wilmot Proviso by William W. Wick and then Stephen Douglas extending the Missouri Compromise line (36°30' parallel north) west to the Pacific, allowing slavery in most of present day New Mexico and Arizona, Las Vegas, Nevada, and Southern California, as well as any other territories that might be acquired from Mexico. The line was again proposed by the Nashville Convention of June 1850.
• Popular sovereignty, developed by Lewis Cass and Douglas as the eventual Democratic Party position, letting each territory decide whether to allow slavery.
• William L. Yancey's "Alabama Platform," endorsed by the Alabama and Georgia legislatures and by Democratic state conventions in Florida and Virginia, called for no restrictions on slavery in the territories either by the federal government or by territorial governments before statehood, opposition to any candidates supporting either the Wilmot Proviso or popular sovereignty, and federal legislation overruling Mexican anti-slavery laws.
• General Zachary Taylor, who became the Whig candidate in 1848 and then President from March 1849 to July 1850, proposed after becoming President that the entire area become two free states, called California and New Mexico but much larger than the eventual ones. None of the area would be left as an unorganized or organized territory, avoiding the question of slavery in the territories.
• The Mormons' proposal for a State of Deseret incorporating most of the area of the Mexican Cession but excluding the largest non-Mormon populations in Northern California and central New Mexico was considered unlikely to succeed in Congress, but nevertheless in 1849 President Taylor sent his agent John Wilson westward with a proposal to combine California and Deseret as a single state, decreasing the number of new free states and the erosion of Southern parity in the Senate.
• Senator Thomas Hart Benton in December 1849 or January 1850: Texas's western and northern boundaries would be the 102nd meridian west and 34th parallel north.
• Senator John Bell (with assent of Texas) in February 1850: New Mexico would get all Texas land north of the 34th parallel north (including today's Texas Panhandle), and the area to the south (including the southeastern part of today's New Mexico) would be divided at the Colorado River (Texas) into two Southern states, balancing the admission of California and New Mexico as free states.
• First draft of the compromise of 1850: Texas's northwestern boundary would be a straight diagonal line from the Rio Grande 20 miles (30 km) north of El Paso to the Red River (Mississippi watershed) at the 100th meridian west (the southwestern corner of today's Oklahoma).

• The Compromise of 1850, proposed by Henry Clay in January 1850, guided to passage by Douglas over Northern Whig and Southern Democrat opposition, and enacted September 1850, admitted California as a free state including Southern California and organized Utah Territory and New Mexico Territory with slavery to be decided by popular sovereignty. Texas dropped its claim to the disputed northwestern areas in return for debt relief, and the areas were divided between the two new territories and unorganized territory. El Paso where Texas had successfully established county government was left in Texas. No southern territory dominated by Southerners (like the later short-lived Confederate Territory of Arizona) was created. Also, the slave trade was abolished in Washington, D.C. (but not slavery itself), and the Fugitive Slave Act was strengthened.