The History of California

Mexican Rule

In 1821, the Mexican War of Independence gave Mexico (including California) independence from Spain. For the next 25 years, Alta California remained as a remote, sparsely populated, northwestern administrative district of the newly independent country of Mexico.
After Mexican independence from Spain, the missions, which controlled most of the best land in the state, were secularized by 1834 and became the property of the Mexican government. The governor granted many square leagues of land to others with political influence. These huge ranchos or cattle ranches emerged as the dominant institutions of Mexican California. The ranchos developed under ownership by Californios (Hispanics native of California) who traded cowhides and tallow with Boston merchants. Beef did not become a commodity until the 1849 gold Rush.
From the 1820s, trappers and settlers from the United States and the future Canada arrived in Northern California. These new arrivals used the Siskiyou Trail, California Trail, Oregon Trail and Old Spanish Trail to cross the rugged mountains and harsh deserts in and surrounding California.
The flag used by Juan Bautista Alvarado in his 1836 independence movement
The early government of the newly independent Mexico was highly unstable, and in a reflection of this, from 1831 onwards, California also experienced a series of armed disputes, both internal and with the central Mexican government. During this tumultuous political period Juan Bautista Alvarado was able to secure the governorship during 1836–1842. The military action which first brought Alvarado to power had momentarily declared California to be an independent state, and had been aided by American and British residents of California, including Isaac Graham. In 1840, one hundred of those residents who did not have passports were arrested, leading to the Graham affair.
One of the largest ranchers in California was John Marsh. After failing to obtain justice against squatters on his land from the Mexican courts, he determined that California should become part of the United States. Marsh conducted a letter-writing campaign espousing the California climate, the soil, and other reasons to settle there, as well as the best route to follow, which became known as "Marsh's route". His letters were read, reread, passed around, and printed in newspapers throughout the country, and started the first wagon trains rolling to California. He invited immigrants to stay on his ranch until they could get settled, and assisted in their obtaining passports.
After ushering in the period of organized emigration to California, Marsh helped end the rule of the last Mexican governor of California, thereby paving the way to California's ultimate acquisition by the United States.

California Republic and conquest

In 1846, a group of American settlers in and around Sonoma rebelled against Mexican rule during the Bear Flag Revolt. Afterwards, rebels raised the Bear Flag (featuring a bear, a star, a red stripe and the words "California Republic") at Sonoma. The Republic's only president was William B. Ide, who played a pivotal role during the Bear Flag Revolt. This revolt by American settlers served as a prelude to the later American military invasion of California and was closely coordinated with nearby American military commanders.
The California Republic was short lived; the same year marked the outbreak of the Mexican–American War (1846–48). When Commodore John D. Sloat of the United States Navy sailed into Monterey Bay and began the military occupation of California by the United States, Northern California capitulated in less than a month to the United States forces. After a series of defensive battles in Southern California, the Treaty of Cahuenga was signed by the Californios on January 13, 1847, securing American control in California.

Early American Period

Following the Treaty of Guadalupe Hidalgo (February 2, 1848) that ended the war, the westernmost portion of the annexed Mexican territory of Alta California soon became the American state of California, and the remainder of the old territory was then subdivided into the new American Territories of Arizona, Nevada, Colorado and Utah. The even more lightly populated and arid lower region of old Baja California remained as a part of Mexico. In 1846, the total settler population of the western part of the old Alta California had been estimated to be no more than 8,000, plus about 100,000 Native Americans, down from about 300,000 before Hispanic settlement in 1769.
In 1848, only one week before the official American annexation of the area, gold was discovered in California, this being an event which was to forever alter both the state's demographics and its finances. Soon afterward, a massive influx of immigration into the area resulted, as prospectors and miners arrived by the thousands. The population burgeoned with United States citizens, Europeans, Chinese and other immigrants during the great California Gold Rush. By the time of California's application for statehood in 1850, the settler population of California had multiplied to 100,000. By 1854, more than 300,000 settlers had come. Between 1847 and 1870, the population of San Francisco increased from 500 to 150,000. California was suddenly no longer a sparsely populated backwater, but seemingly overnight it had grown into a major population center.
The seat of government for California under Spanish and later Mexican rule had been located in Monterey from 1777 until 1845. Pio Pico, last Mexican governor of Alta California, had briefly moved the capital to Los Angeles in 1845. The United States consulate had also been located in Monterey, under consul Thomas O. Larkin.
In 1849, a state Constitutional Convention was first held in Monterey. Among the first tasks of the Convention was a decision on a location for the new state capital. The first full legislative sessions were held in San Jose (1850–1851). Subsequent locations included Vallejo (1852–1853), and nearby Benicia (1853–1854); these locations eventually proved to be inadequate as well. The capital has been located in Sacramento since 1854 with only a short break in 1862 when legislative sessions were held in San Francisco due to flooding in Sacramento.
Once the state's Constitutional Convention had finalized its state constitution, it applied to the U.S. Congress for admission to statehood. On September 9, 1850, as part of the Compromise of 1850, California became a free state and September 9 a state holiday.
During the American Civil War (1861–1865), California was able to send gold shipments eastwards to Washington in support of the Union cause; however, due to the existence of a large contingent of pro-South sympathizers within the state, the state was not able to muster any full military regiments to send eastwards to officially serve in the Union war effort. Still, several smaller military units within the Union army were unofficially associated with the state of California, such as the "California 100 Company", due to a majority of their members being from California.
At the time of California's admission into the Union, travel between California and the rest of the continental United States had been a time-consuming and dangerous feat. Nineteen years afterwards, in 1869, shortly after the conclusion of the Civil War, a more direct connection was developed with the completion of the First Transcontinental Railroad in 1869. California was then easy to reach.
Much of the state was extremely well suited to fruit cultivation and agriculture in general. Vast expanses of wheat, other cereal crops, vegetable crops, cotton, and nut and fruit trees were grown (including oranges in Southern California), and the foundation was laid for the state's prodigious agricultural production in the Central Valley and elsewhere.