Buchanan emphasized opposition to immigration--on cultural as well as economic grounds--and NAFTA in his Republican presidential campaign last year. Perot, the most visible NAFTA critic, has not talked much about immigration, but in his limited comments he has aligned himself with a restrictionist view. "We have got to turn immigration back into a rational process," Perot said on C-SPAN last summer. "We cannot just be a dumping ground in this country when our people are out of work and we're $4 trillion in debt."

In these ways, anxiety over immigration is intertwined with doubts about America's ability to compete in a global economy, the coherence of its national culture in a multiracial society, and a general sense of diminishing opportunities for future generations. In the midst of its wrenching economic downturn--and the aftermath of the devastating 1992 riots--these feelings are particularly strong in California.

"The United States is undergoing a period of tremendous transition," Los Angeles demographer Leo Estrada said. "In periods of uncertainty, we have a tendency to hunker back into a kind of bunker mentality.

"Most of the changes that occur in society are outside the powers of individuals to really deal with, like global economic change," added Estrada, a UCLA professor now on leave. "Immigrants are one of the few tangible targets of change. The vision of them reminds us of the change. . . . It becomes a real easy target to point to as a way of looking at things going on in the world."

In this age of global economic anxiety, these sentiments are hardly unique to America. In Canada, the Western-based populist Reform Party exploded into prominence in recent national elections on a platform that called for reducing immigration. Across Europe, governments are closing borders to immigrants and refugees.

That ominous backdrop frames what many consider the real challenge for policy-makers in Sacramento and Washington: distinguishing between xenophobia and legitimate grievances and defusing the former by dealing responsibly with the latter.

Higham, the historian who studied the cycles of American attitudes toward immigration, said the risk is of failing to impose moderate restrictions today and precipitating an explosive negative reaction later. That, he added, is what happened in the years around World War I, when Congress and President Woodrow Wilson were unable to agree on reasonable steps--and eventually the nation virtually shut the doors to newcomers with the restrictionist and racially tinged immigration laws of the early 1920s.