Last in a three-part series.

WENDOVER — Once, when she heard there was going to be an immigration raid, Maria took her children and hid in the hills surrounding this dusty Utah town that borders Nevada.

It turned out to be a false alarm, but memories of an earlier immigration enforcement effort were enough for Maria, who asked to be identified by only her first name because she lacks legal status in the United States.

"It's something I'm not going to risk," she says in Spanish.

Maria works as a motel maid and hopes to someday be legal, a citizen, like four of her five children who were born in the United States.

However, a situation that seemed hopeful to Maria earlier this year is bleaker now that the Senate has gridlocked on legislation that would have granted legal status to millions of undocumented immigrants.

Meanwhile, the influx continues. Since 2000, more than 500,000 undocumented immigrants have arrived in the United States each year, according to a Pew Hispanic Center report based on 2005 Census data. The center estimates that Utah's undocumented population is between 75,000 and 100,000.

In the absence of congressional reform, the federal government is taking a get-tough approach.

A new Bush administration crackdown on Social Security number misuse was to start this month but is on a temporary hold due to a court challenge. Under the crackdown, employers will have a 90-day window after they receive a letter from the Social Security Administration indicating that a worker's information doesn't match its records. The employers will have to fire employees who can't clear up Social Security discrepancies, or potentially face civil or criminal penalties.

The federal government is also beefing up border security, and undocumented workers say that will make border crossing more expensive, because smugglers, or coyotes, hike their fees.

Efforts to bolster border security will add 18,000 agents along the U.S.-Mexico border by the end of 2008, according to U.S. Customs and Border Protection reports. The total mileage of border fence is set to be expanded to 370 miles, vehicle barriers are being expanded, and a high-tech system of sensors and radar is being installed on a 28-mile stretch of Arizona border.

A dangerous border