<P> The history of Arizona as recorded by Europeans began in 1539 with the first documented exploration of the area by Marcos de Niza, early work expanded the following year when Francisco Vásquez de Coronado entered the area as well . Arizona was part of the state of Sonora, Mexico from 1822, but the settled population was small . In 1848, under the terms of the Mexican Cession the United States took possession of Arizona above the Gila River after the Mexican War, which became part of the Territory of New Mexico . By means of the Gadsden Purchase, the United States secured the northern part of the state of Sonora, what is now Arizona south of the Gila River in 1853 . </P> <P> In 1863, Arizona was split off from the Territory of New Mexico to form the Arizona Territory . The remoteness of the region was eased by the arrival of railroads in 1880 . Arizona became a state in 1912 but was primarily rural with an economy based on cattle, cotton, citrus and copper . Dramatic growth came after 1945, as retirees who appreciated the warm weather and low costs emigrated from the northeast . </P> <P> Major issues in recent years include illegal immigration and a crashing of real estate values caused by the Recession of 2008 . </P> <P> Arizona was a part of northern Mexico in the 1840s; it was remote and poor and seldom had outside contacts . The Mexican population, based in Tucson, was a few hundred, in addition to a presidio garrison of about 100 soldiers . The mission was deactivated in 1828 . South of the Gila River it was mostly in the province of Sonora, and a fragment of Chihuahua in the east . To the north Arizona was nominally part of Alta California and a fragment of Santa Fe de Nuevo México in the east . Together with help from Pima and Papago militia the garrison providing a little protection from a hostile Apache population to the east of the San Pedro River and north of the Gila . In the Mexican--American War, the garrison commander avoided conflict with Lieutenant Colonel Cooke and the Mormon Battalion, withdrawing from the town while the Americans marched through the town on their way to California . In the Treaty of Guadalupe Hidalgo (1848), Mexico ceded to the U.S. the northern 70% of modern - day Arizona above the Sonora border along the Gila River . During the California Gold Rush upwards of 50,000 men traveled through on the Southern Emigrant Trail pioneered by Cooke, to reach the gold fields in 1849 . The Pima Villages often sold fresh food and provided relief to distressed travelers among this throng and to others in subsequent years . </P>

Who traveled through present day arizona and new mexico