A Harvard University Center for American Political Studies/Harris Poll showed that immigration is now voters’ top concern, surpassing health care as the nation’s No. 1 issue. By a 42-38 margin, registered voters selected immigration as the major issue. Given that stories from and about the porous southwest border have dominated the news cycle for months, the poll’s finding aren’t surprising. Mark Penn, the poll’s co-director, said that as the border crisis’ “full nature” became evident, voters’ awareness increased correspondingly.