▁American ▁Society ▁of ▁Civil ▁Engine ers ▁for ▁the ▁completion ▁of ▁I - 7 0 ▁through ▁the ▁can y on . ▁ ▁When ▁the ▁Inter state ▁Highway ▁system ▁was ▁in ▁the ▁planning ▁stages , ▁the ▁western ▁termin us ▁of ▁I - 7 0 ▁was ▁proposed ▁to ▁be ▁at ▁Den ver . ▁The ▁portion ▁west ▁of ▁Den ver ▁was ▁included ▁into ▁the ▁plans ▁after ▁lo bb ying ▁by ▁Governor ▁Ed win ▁C . ▁Johnson , ▁for ▁whom ▁one ▁of ▁the ▁t unn els ▁along ▁I - 7 0 ▁is ▁named . ▁East ▁of ▁Id aho ▁Spr ings , ▁I - 7 0 ▁was ▁built ▁along ▁the ▁cor rid or ▁of ▁U . S . ▁Highway   4 0 , ▁one ▁of ▁the ▁original ▁trans cont inental ▁U . S . ▁High ways . ▁West ▁of ▁Id aho ▁Spr ings , ▁I - 7 0 ▁was ▁built ▁along ▁the ▁route ▁of ▁U . S . ▁Highway   6 , ▁which ▁was ▁extended ▁into ▁Colorado ▁during ▁the ▁ 1 9 3 0 s . ▁ ▁Route ▁description ▁ ▁Colorado ▁River ▁I - 7 0 ▁enters ▁Colorado ▁from ▁Ut ah , ▁concurrent ▁with ▁US   6 ▁and ▁US   5 0 , ▁on ▁a ▁plate au ▁between ▁the ▁north ▁rim ▁of ▁Ruby ▁C any on ▁of ▁the ▁Colorado ▁River ▁and ▁the ▁south ▁rim ▁of ▁the ▁Book ▁Cl iffs . ▁The ▁plate au ▁ends ▁just ▁past ▁the ▁state ▁line ▁and ▁the ▁highway ▁desc ends ▁into ▁the ▁Grand ▁Valley , ▁formed ▁by ▁the ▁Colorado ▁River ▁and ▁its ▁trib ut aries