In 1808, Spain's American colonies, one by one, began to fight for independence. Even before this spirit spread to Mexico, California felt the effects of the rebellions, for Spain's hard-pressed navy could not spare ships to bring supplies to the missions, presidios, and pueblos north of San Diego. Thus, in the dozen years that followed, local authorities relaxed restrictions on trading with non-Spanish merchants so that the colony could survive, and Californians became accustomed to contact with sailors, traders, hunters, and trappers from England, France, Russia, and, of course, the United States.
In 1821, Mexico achieved her independence, and word of this event reached Alta California the following year. The colonial policies of the republic were to be quite different from those of the Spanish monarchy. Not only were Californians allowed to trade with foreigners, but foreigners could also now hold land in the province once they had been naturalized and converted to Catholicism. Under Spain, land grants to individuals were few in number, and title to these lands remained in the hands of the crown. Under Mexican rule, however, governors were encouraged to make more grants for individual ranchos, and these grants were to be outright. Most important, the new Mexican republic was determined to move to "secularize" the missions, to remove the natives and the mission property from the control of the Franciscan missionaries.
This process began in California in 1834. In theory, the Franciscans had administered the mission lands in trust for the natives living there when the missionaries arrived, but few Native Americans benefited from the end of the mission system: although each family was to receive a small allotment from the former mission lands, the few who tried to make a living from these plots gave up after few years. Most of the missions' adobe churches and outbuildings soon fell into disrepair, although priests at some missions struggled to continue their ministry to the Mission Indians. Most of the missions' lands were disposed of in large grants to white Californians or recently-arrived, well-connected immigrants from Mexico. In the ten years before the missions were dismantled, the Mexican government had issued only 50 grants for large ranchos. In the dozen years after the missions were secularized, 600 new grants were made.
A new culture sprang up now in California: the legendary life of the ranchero and his family in a society where cattle-raising and the marketing of beef and hides became the central factors of economic life. With the end of the missions, most local attempts at manufacturing stopped. The California ranchers, their lands generally close to the southern California coast, became more and more dependent on the goods brought by the foreign merchants who came in search of hides. As British, Canadian, and United States settlers moved to Oregon, there was also an inevitable encroachment of non-Mexicans in northern California across that border. And more and more trappers and daring "mountain men" followed their taste for adventure and their search for furs in northern California and across the Sierras further south.
There were a few permanent residents of non-Hispanic birth or descent before 1824, but their numbers increased steadily in the Mexican era. The first United States citizens to come overland to California were trappers led by Jedediah Smith in 1826. The first organized group of settlers from the United States who crossed the Plains to California was the party led by John Bidwell and John Bartleson in 1841. Once in California, Bidwell went to work for Johann August Sutter (1803-1880), the most important of the foreign immigrants in Mexican California. A German-born Swiss businessman, Sutter arrived in San Francisco in 1839 and obtained an enormous grant of 48,000 acres at the junction of the Sacramento and American Rivers, where he established "New Helvetia," a settlement with a fort, orchards, vineyards, and wheatfields. Sutter's fort soon became a stopover for the American settlers who followed the Bidwell party through the Sierras, including survivors of the ill-fated Donner Party of 1846. Besides such settlers, trappers, and hunters there were also sailors who had jumped ship.
Mexico always had trouble ruling her distant province. The last governor sent to California from Mexico City was Manuel Micheltorena who came in 1842. His appearance triggered a local revolt, and he withdrew in 1845. Pío Pico, a local ranchero of part African heritage, became governor. Unofficially, California had achieved home rule. A year later, Mexico faced a still greater challenge. By then, California was home to a native population now reduced to less than 100,000 and to some 14,000 other permanent residents. Of these, perhaps 2,500 were "foreigners," whites of non-Hispanic descent, and of these, probably 2,000 had immigrated from the United States since 1840.