History provides a harsh mirror for California's golden image as a melting pot, a progressive place where the continent ends and the future begins.

And the myth has been further exposed by the recent passage of Proposition 187. For California, despite its multiethnic heritage, has always been intolerant to immigrants during rough economic times. The same rugged individualist traits that drew people to the state in the first place, historians say, also made it inhospitable to latecomers anxious to stake their claims."California has always been a xenophobic state," says Eric Schockman, a political science professor at the University of Southern California. "There's always been this mythology of polyethnic harmony. But in fact, the state has a long history of exclusionary acts against the Irish, the Chinese, the Japanese and Hispanics."

To be sure, the state's legislative history shows that floods of foreigners have always provoked fears over economic and political security. But there is another undeniable characteristic to the cycle of foreign emigration - a few years later, as the economic climate improves, the pendulum always swings back:

- In the 1850s, the nativist members of the Know Nothing Party controlled state legislatures, elected governors and even rioted against Irish and German emigrants. Five years later, the government sought immigrants to fight in the Civil War.

- In the 1950s, under Operation Wetback, the federal government forced as many as 1 million Mexicans - most of them farmworkers - to return home. But in subsequent years, that program and others were dropped, as Congress allowed Cubans, Vietnamese and Chinese to flee to the United States en masse during periods of civil strife.

"From a historian's point of view, tensions will always manifest themselves in these ways (such as Proposition 187)," says Bill Issel, professor of history and urban studies at San Francisco State University. "It's part of a long-term phenomenon in American political history."

In the end, Proposition 187, which will deny most public services to illegal immigrants in the state, will probably prove as ineffective a barrier as the others, historians say.

Consider this: The U.S. Census Bureau says Latinos and nonwhites - many of them immigrants - will outnumber Anglos in California within 15 years. Within 25 years, Latinos alone, who now make up more than 30 percent of the state's population, will outnumber Anglos. And within 45 years, nonwhites and Latinos will outnumber Anglos in the state by a ratio of 2 to 1.

"The mythology and the reality of California came together on Proposition 187," says Schockman. "But now that the mythology is cracked, people can start dealing with the reality."