Glenwood Canyon in Western Colorado was the last obstacle in I-70 across America. They just needed one last 14 mile stretch along the Colorado River to connect with Glenwood Springs. From there the highway was already in place down-river and onto the deserts of Utah.
They blew it.
They chose to follow the old wagon road alongside the Colorado River through the magnificent canyon lined with steep 2,000-foot cliffs of sandstone, shale, limestone and granite. The river snakes between the cliffs, varying unpredictably between a trickle and a torrent depending on recent thunderstorms and last winter’s snowpack a hundred miles away.