MEXICO CITY (AP) - Millions of illegal immigrants in the United States never jumped the U.S.-Mexico border where Congress wants to erect impenetrable walls and President Bush is sending National Guard troops to patrol. They never sneaked in at all.The little-acknowledged reality is that nearly half the estimated 12 million undocumented foreigners in the United States entered on bona fide U.S. visas - and simply never left. Authorities call them "overstays" who have been largely overlooked in the vitriolic debate on immigration. "The southwestern border gets all the attention, but it's staggering the number of people who come and overstay their visa," said Dean Boyd, a spokesman for U.S. Immigration and Customs Enforcement in Washington. "It's a very large-scale problem."
A study by the Washington-based Pew Hispanic Center last month indicated that 45 percent of the undocumented migrants in the United States overstayed legal visas. Confirming those findings or knowing the home country of those who overstay their visas is tricky because U.S. authorities don't track the problem. Immigration authorities also generally don't compare entry and exit information to see who should have left the country.