A pass is a traversable route through rough country, often a range of mountains. “Going over the pass” is a metaphoric phrase commonly used to suggest seeking adventure, new lands, wildness, and refreshed identities. In Glacier National Park, more than two thousand miles of hiking trails are maintained, mostly over passes, so hikers may at least imagine such exploits. The availability of passes for human use has had a great deal to do with settlement, land use, and economic patterns. Marias Pass, on the southern border of Glacier National Park, for instance, is the only feasible route for a railroad in a three-hundredmile north-south reach of the Rockies, and that rail line has had an enormous effect on life along the thousand-mile U.S.-Canadian borderland. Going to the Sun Highway crosses Logan Pass, inside the park; utterly unsuitable for a railway, it’s driven each year by thousands of tourists, many on their way to hike other passes, to profound effect on the social and economic life of northwestern Montana. South Pass in Wyoming is a gentle ramp connecting the valleys of the Platte River system with those of the Green River, and was an important passage on the Oregon Trail.

William Kittredge