Contra Costa County, California
In 1821 Mexico gained independence from Spain. While little changed in ranchero life, the Mexican War of Independence resulted in the secularization of the missions with the re-distribution of their lands, and a new system of land grants under the Mexican Federal Law of 1824. Mission lands extended throughout the Bay Area, including portions of Contra Costa County. Between 1836 and 1846, during the era when California was a province of independent Mexico, the following 15 land grants were made in Contra Costa County.
Treaty of Guadalupe Hidalgo
Mexico had claimed the area in question since winning its independence from the Spanish Empire in 1821 following the Mexican War of Independence. The Spanish Empire had conquered part of the area from the American Indian tribes over the preceding three centuries, but there remained powerful and independent indigenous nations within that northern region of Mexico. Most of that land was too dry (low rainfall) and too mountainous to support many people, until the advent of new technology after about 1880: means for damming and distributing water from the few rivers to irrigated farmland; the telegraph; the railroad; the telephone; and electrical power.