Long-standing chain migration policies that encourage legal immigrants to bring dozens of family members into the U.S. led to an explosion of entries in 2016, 53 percent higher than in 2011, according to a new analysis of Census Bureau data. With an estimated addition of 1.8 million legal and illegal immigrants, 2016 is tied with 1999 for seeing the most enter, about 600,000 more than at the height of the great migration through New Yorks Ellis Island in the 1900s.