<Ul> <Li> The Wilmot Proviso, which was created by Congressman 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 . </Li> <Li> 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 . </Li> <Li> Popular sovereignty, developed by Lewis Cass and Douglas as the eventual Democratic Party position, letting each territory decide whether to allow slavery . </Li> <Li> 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 . </Li> <Li> 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 . </Li> <Li> The Mormons' proposal for a State of Deseret seizing areas from portions of the Mexican Cession but excluding the largest 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, while legitimizing The Church of Jesus Christ of Latter - day Saints . </Li> <Li> 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 . </Li> <Li> 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 slave states, balancing the admission of California and New Mexico as free states . </Li> <Li> 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 of the South at the 100th meridian west (the southwestern corner of today's Oklahoma). </Li> </Ul> <Li> The Wilmot Proviso, which was created by Congressman 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 . </Li> <Li> 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 . </Li> <Li> Popular sovereignty, developed by Lewis Cass and Douglas as the eventual Democratic Party position, letting each territory decide whether to allow slavery . </Li>

Southwest usa - states formerly part of mexico circa 1848