On one side of this spine lies the Pacific Ocean, and on the other, the enormous grassy sea of the Great Plains. Now imagine a footpath that runs along the base of those mountains, following the 'shoreline' between the mountains and the plains--twisting through stream gullies, unraveling over low ridges and around buttes--not merely for 10 or 20 or 100 miles, but running on and on for 2,000 or 3,000 miles. For thousands of years, the inhabitants of North America trod along it--first on foot, then with dogs pulling cargo-laden travois, and finally with horses. Over the trail they carried trade goods--such as obsidian for spearheads and seashells form the coast--visited relatives in neighboring bands, set off on sacred missions or went to war with enemy tribes. Restless young men followed it alone for months at a time, driven to seek out a mate or satisfy a curiosity about new lands. The earliest humans who crossed from Asia may have walked this route when they migrated south to populate the Americas at least 15,000 years ago. This would make it the oldest and longest trail on the continent. . . . " [Stark, Peter. 'The Old North Trail..' Smithsonian. Washington, DC. VOL 28, Number 4, July 1997. pps. 54-66. ]