As a former Idaho State Historian and Associate Director of the Idaho State Historical Society, Petersen's fascination with history has been expressed throughout his career. The author of numerous articles and books about the Northwest, he is the only person to have twice received the Idaho Book Award.

Petersen received the first annual Award for Outstanding Achievement in the Humanities from the Idaho Humanities Council in 1986, the Presidential Medallion from Lewis-Clark State College in 2006, and an Honorary Doctorate in Humane Letters from the University of Idaho in 2014.