Matthias Doepke was impressed when he moved to America as a graduate student in the 1990s. Academic pay was better than in his native Germany and university departments were slick and organised. But what he appreciated most was the attitude. “You come to the US and you have this feeling that you are totally welcome and you’re totally part of the local community,” he says. In 2012 he became a professor of economics at Northwestern University in Illinois, and in 2014 became a naturalised citizen.