Donald Trump's candidacy isn't the first time the Republican Party has been split by an outsider declaring war on the establishment elite.

Immigration has been a defining issue in a campaign before, and the consequences transformed the Democratic Party.

Trump has used populist politics to appeal to voters who are fed up with the status quo. We look at another politician who tapped into America’s divisions decades ago: George Wallace.

In the latest installment of our “What Happens Next” series examining the future of society, we visit Medellín, Colombia—a city that has reinvented itself over the past few decades, turning its violent past into a sustainable future by transforming its slums.