Immigration has become an increasingly contentious political and social issue around the country.
Organizations patterned after the controversial "Minuteman Project" along the US-Mexico border have sprung up in New England, the Midwest, the South, and the Pacific Northwest. This has led to demonstrations and shouting matches with those opposed to what they call "vigilantes."
State and local officials are working to limit government services to illegal immigrants and their children (such as college tuition and worker's compensation), requiring proof of citizenship to get a driver's license and cracking down on day labor sites where men - many in the country illegally - gather to seek work.
Concerns over terrorism, identity theft, and the national methamphetamine epidemic (which is fueled by Mexican drug cartels and Hispanic gangs operating far from the border) are part of the picture. But some observers warn of an upsurge in "nativism" - the kind of anti-immigrant feeling that has swelled at other times in US history.
"This is a really significant issue right now," says Mark Pitcavage, a historian of extremist movements with the Anti-Defamation League and an adviser to law-enforcement agencies.
For years, says Dr. Pitcavage, some organizations have been critical of what they see as lax immigration policies promoted by both Republican and Democratic administrations.
There are about 11 million illegal immigrants in the US today, a figure that grows by some 500,000 a year, according to the Center for Immigration Studies. In a recent paper, the center's research director, Steven Camarota, reports that there now are more than 35 million immigrants (legal and illegal) living in the US. That amounts to more than 12 percent of the total population, the highest percentage in eight decades.
While many illegal immigrants enter the country to do jobs most US citizens shun, the National Research Council has estimated that the net cost of immigrants ranges from $11 billion to $22 billion a year. Camarota notes that the proportion of immigrant-headed households using at least one major welfare program is 29 percent, compared with 18 percent for native households.
Many immigration reformers are concerned that the kind of temporary guest worker program President Bush, businesses, and some members of Congress favor will exacerbate the situation.
"They need to fix the system," said Dan Stein, president of the Federation for American Immigration Reform, in a fund-raising message. "Not only do they need to make the enforcement commitments work, they need to reduce immigration ... and eliminate the nepotistic family chain migration system that fuels the seeds of unmanageable immigration growth."
Recently, that concern about immigration has developed into a widespread political movement. But it's also developed more radical offshoots.
"Not surprisingly, when you see a movement like this emerge, you see extremists actively working to exploit that mainstream sentiment ... as a wedge to recruit or to propagandize," says Pitcavage.
Devin Burghart of the Center for New Community, a faith-based human rights organization in Chicago, estimates that the "Minutemen" have spawned at least 40 new groups in more than a dozen states.
In some areas, the rise in extreme anti-immigrant sentiment has resulted in attacks on Hispanic men, and conspiracy theories. One theory warns of "la reconquista," the invasion of the US southwest by Mexicans determined to take back territory lost in the 19th century.
Movement across the US-Mexico border has gone on for centuries, says Jean Rosenfeld, of the UCLA Center for the Study of Religion. But today, says Dr. Rosenfeld, "The nativist narrative ... signals a high tide of resurgent xenophobia."
While communities from New England to the Pacific Northwest are seeing notable growth in the Hispanic population, the most dramatic increases have been in the South, reports the Pew Hispanic Center. Most of those migrants are men who lack legal status, reports Pew.
Since the last census, the Hispanic population in Georgia has grown faster than any other state. The need for laborers to accommodate the residential and commercial building boom around Atlanta is a big part of that. The rate of Hispanic births is twice the official Hispanic population there. Anti-immigration activists opposed to multiculturalism have taken to calling the state "Georgiafornia."
In Washington this year, Congress and the Bush administration are expected to continue wrangling over immigration reform. But most of the action, observers say, is likely to be at the state level: legislation and ballot initiatives.
In 2004, Arizonans approved Proposition 200, which requires proof of citizenship to vote or to apply for state benefits. Up to a dozen states could have similar measures on the ballot this year. Lawmakers in North Carolina and New Hampshire are considering proposals authorizing state and local law officers to enforce federal immigration law. Massachusetts state representatives recently defeated a bill that would have allowed undocumented immigrant students to pay the same discounted college tuition rate as state residents.
In the post-9/11 era, attitudes toward foreign immigration are unique in some ways. But there are similarities to the 1850s and the early 20th century, when violent reactions to immigrants - charges that they took jobs, caused crime, and were not loyal to the US - were common.
"I mean from Germans to Irish Catholics to Jews to Hispanics virtually the same kinds of things have been said," says Mark Potok of Southern Poverty Law Center, who monitors extremist activities in the US. Such sentiment historically abates, says Pitcavage. "The sooner we get this cycle over with, the happier I'll be."