"Since 1996, Congress has called on the Federal government to create a tracking system that could record the entry and exit of foreign nationals. With over 327 official land, air, or sea ports of entry and roughly 440 million total border crossings each year, tracking the entry and exit of foreign nationals is no small task. While several initiatives were started, in 2003, the Department of Homeland Security created the United States Visitor and Immigrant Status Indicator Technology or 'US-VISIT,' system to meet the original statutory mandate as well as many other laws, including requirements for a biometric system. US-VISIT is an important part of the Department's layered border security approach and fight against terrorist travel. In ten years, our nation's entry-exit system has gone from a mostly paper-based system to an automated program that now uses biometrics and draws on a number of databases. Since January 2004, US-VISIT has processed more than 76 million visitors and intercepted approximately 1,800 immigration violators and people with criminal records. ICE apprehended 139 aliens based on overstay records identified by US-VISIT in FY 2006 and the numbers are anticipated to rise as biometrics become more prevalent."
Committee on Homeland Security: http://homeland.house.gov/