While the U.S. Congress and President George W. Bush proceed with their respective plans to erect an impenetrable wall along the Mexican border and to deploy National Guard reinforcements to the area, almost half of the approximately 12 million undocumented immigrants in the United States never crossed the border illegally and, in fact, entered the country legally.

The government is reluctantly admitting that a good five million illegal immigrants entered the United States on legal visas, but “forgot” to return home. They are known as overstayers, and it is not expedient to refer to them during heated debates over immigration reform.

“Everyone’s attention is focused on the southern border of our country, where there is a flow of illegal immigrants, but a great number of people entered the country legally and simply overstayed their visas,” said Dean Boyd, a spokesman for U.S. Immigration and Customs Enforcement. “It’s a huge problem.”

According to the National Center for the Spanish-speaking Population, 45 percent of undocumented immigrants overstayed visas. However, it is not easy to verify the accuracy of this figure or to determine countries of origin because the federal government does not keep records or compare information regarding dates of entry and departure-measures that would help uncover the “overstayers.”

“These people are hiding, they don’t want to be found,” explained Boyd.

To find work, some undocumented immigrants “borrow” Social Security numbers from legal residents or use forged documents. Others become servants, gardeners or cleaners, going into jobs that rarely require documents.

In 2005, the State Department issued almost 5.4 million nonimmigrant visas for temporary stays, 17 percent of which went to Mexicans. These types of visas are issued for a variety of purposes, including tourism, business, medical treatment and education.

It is no small task to obtain such a visa. Lines at the U.S. Embassy in Mexico City start forming overnight. An interview appointment alone costs a $100, and the applicant has to prove that he or she has a job, savings, a home and a family in their home country. Approximately 70 percent of applications are granted.