If you want to move up in America, go to college. That’s the advice people get. And there’s loads of evidence that a college degree will improve your economic prospects. But a new project by a group of economists shows that some colleges are doing a much better job than others when it comes to promoting social mobility. In fact, some colleges are doing more to exacerbate class divides than to help people move up. We visit a college coming to terms with its own role in perpetuating class divides and another that has long been a “mobility maker” – but is struggling to stay that way.