Gadsden Purchase in the context of "American Southwest"

The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that includes Arizona and New Mexico, along with adjacent portions of California, Colorado, Nevada, Oklahoma, Texas, and Utah. The largest cities by metropolitan area are Phoenix, Las Vegas, El Paso, Albuquerque, and Tucson. Before 1848, in the historical region of Santa Fe de Nuevo México as well as parts of Alta California and Coahuila y Tejas, settlement was almost non-existent outside of New Mexico's pueblos and Spanish or Mexican municipalities. Much of the area had been a part of New Spain and Mexico until the United States acquired the area through the Treaty of Guadalupe Hidalgo in 1848 and the smaller Gadsden Purchase in 1854.

While the region's boundaries are not officially defined, there have been attempts to do so. One such definition is from the Mojave Desert in California in the west (117° west longitude) to Carlsbad, New Mexico, in the east (104° west longitude); another says that it extends from the Mexico–United States border in the south to the southern areas of Colorado, Utah, and Nevada in the north (39° north latitude). In another definition, the core Southwestern U.S. includes only the states of Arizona and New Mexico; others focus on the land within the old Spanish and Mexican borders of the Nuevo México Province or the later American New Mexico Territory.

Arizona is a landlocked state in the Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the northwest and California to the west, and shares an international border with the Mexican states of Sonora and Baja California to the south and southwest. Its capital and largest city is Phoenix, which is the most populous state capital and fifth-most populous city in the United States. Arizona is divided into 15 counties.

Arizona is the sixth-largest state by area and the 14th-most-populous of the 50 states. It is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912. Historically part of the territory of Alta California and Nuevo México in New Spain, it became part of independent Mexico in 1821. After being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848, where the area became part of the New Mexico Territory. The southernmost portion of the state was acquired in 1853 through the Gadsden Purchase.

Franklin Pierce served as the 14th president of the United States from March 4, 1853, to March 4, 1857. Pierce, a Democrat from New Hampshire, took office after defeating Whig Party nominee Winfield Scott in the 1852 presidential election. Seen by fellow Democrats as pleasant and accommodating to all the party's factions, Pierce, then a little-known politician, won the presidential nomination on the 49th ballot of the 1852 Democratic National Convention. His hopes for reelection ended after losing the Democratic nomination at the 1856 Democratic National Convention. He was succeeded by Democrat James Buchanan.

Pierce vetoed funding for internal improvements, called for a lower tariff, and vigorously enforced the Fugitive Slave Act of 1850. Influenced by the Young America expansionist movement, the Pierce administration completed the Gadsden land purchase from Mexico, clashed with Great Britain in Central America, and led a failed attempt to acquire Cuba from Spain. Pierce's administration was severely criticized after several of his diplomats issued the Ostend Manifesto, which called for the annexation of Cuba, by force if necessary. His popularity in the Northern free states declined sharply after he supported the 1854 Kansas–Nebraska Act, which nullified the Missouri Compromise. Passage of the act led directly to a long and violent conflict over the expansion of slavery in the Western United States.