The confluence of the Green and Colorado Rivers, now in Canyonlands National Park, near popular tourist destination Moab, still cannot be reached or viewed easily. Much of the surrounding region remained remote and rarely visited for decades after settlement of other parts of the West. The first US government expedition to explore the canyon country and the Four Corners area was led by John Macomb of the army's topographical engineers.

The soldiers and scientists followed in part the Old Spanish Trail, whose location they documented and verified. Seeking to find the confluence of the Colorado and the Green and looking for alternative routes into Utah, which was of particular interest in the wake of the Utah War, they produced a substantial documentary record.

The book is published by Utah State University Press. The audiobook is published by University Press Audiobooks.

"A fascinating study and significant contribution to our understanding of the Southwest." (Will Bagley, author of Blood of the Prophets: Brigham Young and the Massacre at Mountain Meadows)