immigration
© unknownDocumenting immigrants, an exit-entry dilemma.
Nearly half a million foreigners who legally entered the US last year, stayed in the country despite the expiration of their visas, the Department of Homeland Security (DHS) says. In an "Entry/ Exit Overstay Report" that was published on Tuesday, the DHS stated that, out of the some 45 million people who were granted non-immigrant admissions to the US in 2015, a total of 527,127 overstayed their visas.

As of January 4, 2016, up to 416,500 of those individuals were still believed to be in the country, violating the terms of their visas. This is while the report did not account for the people who might have illegally entered America in the same period. According to Pew Research Center, there were 11.3 million unauthorized immigrants living in the US in 2014. The DHS officials were slated to testify about the findings at a Senate Judiciary Committee hearing on Wednesday.

Congress ordered the department to conduct reports on visa overstays in 1997. Lawmakers have been asking the DHS for years to provide the data, only to be told that the data could not be compiled.

The department has also been tasked with improvising an "exit-entry system" capable of accurately tracking all people entering and leaving the US. Foreigners who apply for the US are interviewed, photographed and have their fingerprints taken before heading there. However, the US Customs and Border Protection is unable to get those biometric information from every departing foreigner. This makes it tricky to figure out who has left and who has remained.

Another complicating factor is the way American airports are laid out. Unlike many foreign airports that have dedicated terminals for domestic and international flights, US airports use the same terminal for all departures.

The White House and lawmakers have said that they are reviewing major changes to visa programs following a terror attack in December 2015, where two alleged Daesh (ISIL) sympathizers killed more 21 people in San Bernardino, California. One of the attackers involved in the shooting entered the US on a fiancée visa, another type of entry program that is currently undergoing revision.

In the wake of the attack, Washington passed a law, excluding from its Visa Waiver Program, dual nationals from Iran, Iraq, Syria and Sudan as well as anyone else who has traveled to those countries in the past five years.