In 1850, 9.7 percent of the US population was foreign-born, according to the Pew Research Center. By 1890, it had jumped to 14.8 percent, spurring Hall into action. In 1920, though, that figure began its steady drop, and by 1970 it had plummeted to 4.7 percent.
By 2015, fueled largely by surging immigration from Latin America, it had rebounded to 13.7 percent, nearly the same level that Hall had found so intolerable at the start of his crusade.
But you can figure it out from this graph, which clearly shows the flood in (non-European) immigration after 1965: