In Divided States of America, FRONTLINE set out to examine how the Obama presidency gave way to one of the most polarized eras in American history. In making the documentary, our journalists conducted dozens of interviews over hundreds of hours. They spoke to top White House officials, members of Congress from both parties, experienced reporters and other key experts. This collection of 21 extended interviews draws from that body of reporting, offering an inside look at the Obama years. It traces key moments that fueled the partisan divide, and examines the state of the nation that Donald Trump inherits as president.