Not only that, the Gold Rush precipitated an era of unprecedented animosity toward Mexican people living in the state, a xenophobia that trained its stare not only on Californios and newer arrivals from Mexico, but on other Latinos, such as the Chileans and Peruvians, as well.

Most of the trouble began around 1850, in the so-called "southern mines" of Calaveras and Tuolumne counties. Many Mexicans from the rich mining state of Sonora had come to the area east of Stockton -- where the foothill town of Sonora, not coincidentally, now sits -- to try their luck in the mines.

At first, they staked their claims and mined in relative peace alongside all of the other gold-seekers arriving
daily in California. They were admired for the well-honed "dry digging" skills they had developed in their native land, techniques that brought them a modicum of early success.

But it wasn't long before Anglo miners and eastern politicians, their own numbers growing in California,
launched a campaign to force the Sonorans from the mines.

The Treaty of Guadalupe Hidalgo, which ended the Mexican War, had given the United States official possession of California just nine days after James Marshall had discovered gold in Coloma on Jan. 28, 1848.

In a little over two years, Americans came to resent the fact that foreigners -- particularly those from a country the United States had just defeated in war -- were making it rich off land that they now considered exclusively theirs.

State lawmakers found an equally effective cure for ridding the mines of Mexican gold seekers when they adopted the Foreign Miners' Tax Law of 1850.

The statute required non-U.S. citizens to pay $20 a month -- a costly sum at the time -- for the privilege of panning or digging for gold. Many Mexican and some French miners protested the new law, almost to the point of violence, but in the end, most simply left the Sierra.

Their departure left a gaping hole in the economy of the Central Valley, particularly in Stockton, where civic leaders demanded a repeal of the tax, which was adopted in 1851. Still, it was too late. The Mexican miners would not come back.