DesertUSA: John Wesley Powell: A detailed biographical overview.
Major John Wesley Powell: Biography of the explorer of the Colorado River, from the John Wesley Powell Memorial Museum.
The American Experience: Lost in the Grand Canyon: Companion site to the PBS series about Powell's Colorado River journey. With timeline, maps, and program information.
The Powell Expedition: A map and account of the events of the Colorado River expedition.
The Story of Major John Wesley Powell: A biography from Canyon Country Online.