Peter van Agtmael was 20 on September 11, 2001. Like many Americans who came of age at the time, the attacks shook his worldview. He spent the next decade thinking about questions of race, nationality, history, and class. As a photographer, he was first embedded with U.S. troops on the battlefields of Iraq and Afghanistan, then back home following the lives and the families of soldiers wounded in battle.

But van Agtmael realized that if he wanted to dig deeper into how America has changed in the years since 9/11, he needed to look beyond the insular world of the military.

In 2009, van Agtmael continued his search, this time within the 50 states. He and a friend embarked on what would