India, Feb. 13 -- Standing beneath a tangled canopy of highway overpasses at the edge of a muddy bluff, I watched the Missouri River churn below me. Its murky water rolled relentlessly onward, folding into eddies as it wound its way toward the Mississippi. Hundreds of years ago, this treacherous brown ribbon marked the frontier's edge; it was where the West got wild. Of course, I knew that since then, the land beyond the river has been charted, settled, tamed-and yet it still felt as if I was standing at the precipice of an inscrutable void.

I strained my eyes, probing the distant horizon across the river. Nearly 2,000 miles-and an untold number of impediments-separated me from my destination. My journey would begin in St. Joseph, Missou...