When John Wesley Powell explored the Colorado Plateau, he marveled at the complex maze of canyons.
Every river … has cut another canyon; every lateral creek has cut a canyon; every brook runs in a canyon; every rill born of a shower and born again of a shower and living only during these showers has cut for itself a canyon; so that the whole upper portion of the basin of the Colorado is traversed by a labyrinth of these deep gorges.
The one-armed Powell, having lost his right arm in the Battle of Shiloh while fighting for the Union during the Civil War, began his epic voyage down the Green and Colorado Rivers on May 4, 1869, then 35 years old, with four boats and eleven men. One of the men quit after a month, and three others left after two months. But three months and 900 miles after the start, the remaining party emerged from the mouth of the Grand Canyon.

Powell wrote of the expedition in Exploration of the Colorado River and Its Canyons, published in 1875 to much acclaim. In the interim, he had continued to explore and survey the Colorado Plateau region, including a repeat trip down the Green and Colorado Rivers in 1871-72, which also contributed to the book. During his career, he played a major role in founding the U.S. Geological Survey and was also one of the founders of the National Geographic Society.

Recognizing the American West was not only shaped by water, but that any settlement of the West would be dependent on water, a scarce resource in this dry region, Powell followed his Exploration with Report on the Lands of the Arid Region of the United States in 1878. In the report, he offered the bold idea of a gradual settlement of the West based on hydrologic studies that identified where irrigation was feasible, rather than an all-out land rush. As might be expected, politicians ignored his recommendation. Still, he served as the second chief of the U.S. Geological Survey with further exploration of western lands and as the first director of the Smithsonian Institution’s Bureau of Ethnology where he oversaw a group of ethnologists documenting the vanishing culture of Native Americans in the West and South.