Roughly 304,000 foreigners arrived at U.S. airports and seaports legally in 2015 but then overstayed their visas until at least January 2017, according to a new report by the Department of Homeland Security. The numbers show that more than half of the nation’s new 2016 illegal aliens arrived legally at airports and seaports, instead of sneaking across a land border, said Steve Camarota, a data expert at the Center for Immigration Studies. The overall inflow was about 550,000 illegals in 2016, he said. Roughly 1.47 percent of visitors overstay their visas, but many leave a few months later. For example, 740,000 of 50 million 2016 visitors overstayed their visas in 2016, but 2o0,000 went home by December 2016, leaving roughly 540,000 of them illegally living in the United States on January 10, 2017. The 2015 and 2016 overstays added up to 850,000 illegal immigrants in early 2017. Overall, overstays are thought to comprise roughly 40 percent of the widely accepted claim of 11 million resident illegals. Agency officials are testing a new system to track the departures of visitors and so identify people who illegally overstay their visas. The tracking system was put on a fast track to deployment by President Donald Trump in February, alongside his push to extend the nation’s walls and fences along the border with Mexico. During the tenure of former President Barack Obama, his DHS appointee did little to track or reduce the number of people who overstayed their visas. The 304,000 long-term overstays from 2015 are part of the broader overstay rate, which showed almost 629,000 tourists, contract workers, and other foreigners were in-country at the end of October 2016 after their recent visas had expired. Some of those 629,000 overstaying visitors returned home in the weeks and months after their visas expired. Roughly one-in-20 recent foreign students and “exchange visitors” overstayed their visa for at least a short period, said a press statement from the agency.