Sketch map or diseño of Rancho Providencia, 1840s.
It was not until the Mexican era (1821–1846) that the land was actually granted to individuals. In 1821, Mexico achieved its independence from Spain, and California came under control of the Mexican government. The 1824 Mexican Colony Law established rules for petitioning for land grants in California; and by 1828, the rules for establishing land grants were codified in the Mexican Reglamento (Regulation). The Acts sought to break the monopoly of the missions and also paved the way for additional settlers to California by making land grants easier to obtain. The procedure included a 'diseño' – a hand drawn topological map. The Mexican Governors of Alta California gained the power to grant state lands, and many of the Spanish concessions were subsequently patented under Mexican law.
Through the Secularization Act of 1833, the Mexican government repossessed most of the lands that had been provided to the missions by the Spanish crown. Secularization was implemented between 1834 and 1836. The padres could only keep the church, priest's quarters and priest's garden. A commissioner would oversee the crops and herds, while the land was divided up as communal pasture, a town plot, and individual plots for each Indian family.
The number of Mexican land grants greatly increased after the secularization of the California missions in 1834. Although the original intent of the secularization legislation was to have the property divided among former mission Indians, most of the grants were made to influential Californios of Spanish background.
The Mexican grants were provisional. The boundaries had to be officially surveyed and marked. The grantee could not subdivide or rent out the land. The land had to be used and cultivated. A residential house had to be built within a year. Public roads crossing through the property could not be closed. If the provisional conditions were not met, the land grant could be 'denounced' by another party who could then claim the land.
The United States declared war against Mexico on May 13, 1846. Action in California began with the Bear Flag Revolt on June 15, 1846. The authority and jurisdiction of Mexican officials terminated on the 7th of July, 1846, the day the forces of the United States took possession of Monterey, the capital of California. Armed resistance ended in California with the Treaty of Cahuenga signed on January 13, 1847. The Treaty of Guadalupe Hidalgo, ending the war, was signed February 2, 1848 and California became a Territory of the United States. Between 1847–1849, California was run by the U.S. military. A constitutional convention met in Monterey in September 1849, and set up a state government that operated for 10 months before California was admitted to the Union as the 31st State by Congress as part of the Compromise of 1850, enacted on September 9, 1850.