s ▁constructed ▁off site ▁and ▁lifted ▁in ▁place ▁to ▁minim ize ▁the ▁environmental ▁foot print . ▁The ▁grade ▁over ▁V ail ▁Pass ▁reaches ▁seven ▁percent . ▁ ▁Glen wood ▁C any on ▁ ▁Glen wood ▁C any on ▁has ▁served ▁as ▁the ▁primary ▁transport ation ▁ar tery ▁through ▁the ▁Rock y ▁Mountains , ▁even ▁before ▁the ▁creation ▁of ▁U . S . ▁high ways . ▁Rail ro ads ▁have ▁used ▁the ▁can y on ▁since ▁ 1 8 8 7 ▁and ▁a ▁d irt ▁road ▁was ▁built ▁through ▁the ▁can y on ▁in ▁the ▁early ▁ 2 0 th ▁century . ▁The ▁first ▁p aved ▁road ▁was ▁built ▁from ▁ 1 9 3 6 ▁to ▁ 1 9 3 8 ▁at ▁a ▁cost ▁of ▁$ 1 . 5 ▁million ▁( equ ivalent ▁to ▁$ ▁million ▁today ). ▁ ▁With ▁the ▁Eisen h ower ▁T unnel ▁finished , ▁the ▁last ▁remaining ▁obst acle ▁for ▁I - 7 0 ▁to ▁be ▁an ▁inter state ▁commercial ▁ar tery ▁was ▁the ▁two ▁l ane , ▁non - fre ew ay ▁portion ▁in ▁Glen wood ▁C any on . ▁Const ruction ▁had ▁started ▁on ▁this ▁section ▁in ▁the ▁ 1 9 6 0 s ▁with ▁a ▁small ▁section ▁opening ▁to ▁traffic ▁in ▁ 1 9 6 6 . ▁The ▁remainder ▁was ▁stopped ▁due ▁to ▁environmental ist ▁protest s ▁that ▁caused ▁a ▁ 3 0 - year ▁controvers y . ▁The ▁original ▁design ▁was ▁critic ized ▁as ▁" the ▁ep it ome ▁of ▁environmental ▁ins ens itivity ". ▁Engine