For almost 40 years, Mark Peterson has worked as a photographer, but never have his shots seemed more vital and timely. He has captured some of the most pointed and provocative photos of American political life, pulling back the curtain and revealing a world of theatrics and spectacle. But arguably, his most important work has focused on some of his country's ugliest moments. The surge of white nationalism under Donald Trump has left the award-winning photographer trying to capture a country he has trouble understanding.