Alta California (English: Upper California) was a province and territory in the Viceroyalty of New Spain and later a territory and department in independent Mexico. The territory was created in 1769 out of the northern part of the former province of Las Californias, and consisted of the modern American states of California, Nevada, Arizona, Utah, western Colorado and southwestern Wyoming. The territory passed to American control after the Mexican–American War and ceased to exist with the creation of the State of California in 1850.
Although the Spanish had explored the coastal area of Alta California as early as the sixteenth century and considered the area as the domain of the Spanish monarchy, they made no efforts to settle the area until the eighteenth century, when other European powers—in particular Russia—began exploring the area. In preparation for settlement, the northern, mainland region of Las Californias was granted to Franciscan missionaries to convert the Native population to Catholicism, following a model that had been used for over a century in Baja California. The Spanish Crown funded the construction and subsidized the operation of the missions, with the goal that the relocation, conversion and enforced labor of Native people would enforce Spanish rule. The first mission was established in San Diego in 1769. In 1773 a boundary between the Baja California missions, controlled by the Dominicans, and those of Alta California was set by Francisco Palóu. The missionary effort was followed by the construction of presidios and pueblos, which were to be manned and populated by Hispanic people. The first pueblo founded was San José in 1777, followed by Los Ángeles in 1781.
By law mission land and property were to pass to the resident Native Americans of California after a period of about ten years, when the natives would become Spanish subjects. In the interim period, the Franciscans were to act as mission administrators who held the land in trust for the Native residents. The Franciscans, however, prolonged their control over the missions and ran them for more than sixty years. The transfer of property never occurred.