Critics accused President James Monroe and Secretary of State Adams of leaving Texas with legitimate claims, which fueled subsequent calls for an “annexation” of Texas, particularly from supporters of slavery in the 1830s. In addition, the Adams Onís Treaty confirmed Mexican possession of land intended for U.S. expansion during the war with Mexico from 1846 to 1848. The legislative branch of 20Mexico then refused to ratify the agreement, believing that the independence of Texans was the first step in the United States. Expansion to the southwest. See Weber, ed., Foreigners in Their Native Land: Historical Roots of the Mexican Americans: 114-115. Eventually, Gadsden reached an agreement with Mexico to buy about 30,000 square miles for $10 million. Gadsden Purchase or Treaty was an agreement between the United States and Mexico in 1854, in which the United States agreed to pay $10 million to Mexico for a 29,670-square-mile portion of Mexico, which later became part of Arizona and New Mexico. The Gadsden purchase provided the land needed for a southern transcontinental railroad and attempted to resolve the conflicts that lasted after the Mexican-American War. The South Pacific portion of Arizona was originally largely in the Gadsden Purchase, but the western portion was later diverted north of the Gila River to serve the city of Phoenix (as part of the PE&SW purchase agreement).
The part of New Mexico largely crosses the area that made the obstructor between Mexico and the United States after the entry into force of the Treaty of Guadalupe Hidalgo and before the purchase of Gadsden. . . .