The accidental highway

Glenwood Canyon on the Western Slope of Colorado has been in the news lately, thanks to a big rockslide that happened just after midnight on March 9. The tumbling boulders blocked and damaged a stretch of Interstate 70. It took four days to get the highway open again, just on a limited basis. During the closure, motorists traveling between Denver and Grand Junction faced a 200-mile detour.

So how did a narrow canyon with high and steep walls become a vital transportation corridor? Mostly by happenstance.

There's no evidence that the area's aboriginal inhabitants, the Utes, ever used the canyon in their travels between summer hunting grounds and winter quarters . Nor did French traders or Spanish explorers or the American mountain men of yore.

Instead, the route is the result of Aspen, where prospectors found rich silver ore in 1880. The place was seriously isolated. One railhead was at Balltown, a few miles south of Leadville, and getting to Aspen meant crossing 12,095-foot Independence Pass. Another route, from the railhead at Crested Butte, involved hard freighting over Schofield Pass.

Had Aspen just been a flash in the pan, like so many other mining camps, it might have stayed isolated. But its mines kept producing as that decade wore on, and so the railroads saw potential profit in serving it.

Two interested lines had already reached Leadville, just 32 miles away as the figurative crow flies, but on the other side of the highest peaks in the Rocky Mountains. One railway, the standard-gauge Colorado Midland, started building immense trestles and a tunnel under the Great Divide at Hagerman Pass. The rails went down the Fryingpan River to Basalt, then turned up the Roaring Fork to reach Aspen.

The other, the narrow-gauge Denver & Rio Grande, had already extended from Leadville, crossing Tennessee Pass to serve mines in the Red Cliff area. In 1887, that branch was extended for 104 miles down the Eagle River to its junction with the Colorado River (then called the Grand), down the Colorado via Glenwood Canyon to the Roaring Fork at Glenwood Springs, then up the Roaring Fork to Aspen.

The Rio Grande beat the Midland to Aspen. Those tracks down Glenwood Canyon might have just been a long branch line, to be abandoned after the mines played out, since the Rio Grande already had a route to Grand Junction and points west -- the Marshall Pass line that ran west from Pueblo through Salida, Gunnison and Montrose.

Thanks to competitive pressure from the Midland, the Rio Grande standard-gauged the Glenwood Canyon line in 1890, and joined with the Midland in building a joint line down the Colorado River to Grand Junction. Since it was standard-gauge, it evolved into the main line, now part of the Union Pacific system -- the Midland was scrapped in 1919.

That's the railroad part of the story, one you can see with a ticket on Amtrak's California Zephyr. As for roads, the old highway to Glenwood Springs from the east skirted the canyon by leaving the river at Gypsum and climbing Cottonwood Pass to the south before dropping down into Glenwood Springs. In 1937, likely using Depression-era stimulus funds, the Colorado Highway Department built a two-lane highway down Glenwood Canyon that would eliminate the grades of Cottonwood.

When the interstate highway system was proposed in 1956, west-bound Interstate 70 was supposed to dead-end in Denver. Colorado politicians lobbied and pulled strings to get the feds to support a route into the mountains (supposedly, the national defense required that the driving time between Denver and Los Angeles be shorted by a couple of hours).

Whether the route would go through Glenwood Canyon was a contentious matter, though. Construction of a four-lane highway through the narrow defile would be hideously expensive, and it could trash out a beautiful canyon (though certainly not a pristine one, what with the existing highway, the railroad, and the Shoshone Hydroelectric Plant).

Opponents wanted the Interstate to use the old route over Cottonwood Pass. I've been over it on the county back roads, but I don't remember it very well. It was about 25 years ago, and Allen Best and I were on an beater-pickup tour of the Western Slope that involved stops at the Gold Pan in Breckenridge and the Midland Saloon in Basalt, among other things.

Glenwood Canyon got the nod, and the highway engineers set out to prove that it could be done without trashing the place. It took 12 years of construction and when it opened in 1992, it was the last segment of the national interstate system to be completed. But they did a great job of maintaining the canyon's charms -- the first time I drove it after completion, I thought "Finally, Colorado did something right."

Even so, since the law of gravity remains in effect, and because once-stable rock can come loose with thawing and freezing, there will always be rockslides, no matter how well the highway was built.

And if it hadn't been for the silver mines of Aspen and some competing mountain railroads, Glenwood Canyon might today be a scenic national park, like the Grand Canyon or Black Canyon of the Gunnison, instead of an important transportation route whose closure caused major complications.