This newspaper clipping from 1933 I found confirmed that there indeed was a plan to do this at one point, with perhaps a tunnel to avoid the cliffs on the West side:
I find this kind of history quite interesting. The wikipedia page for Mosca Pass mentions it used to be traversed by CO-150, but it is now just a hiking trail on the West side. Is anyone aware of any other "lost" roads around the state?NEW HIGHWAY ON WHISKEY PASS IS NEARING SUMMIT
I ■ The new highway up Whiskey pass 1 east of San Luis, has been completed to a point about twenty miles from 1 the Costilla county seat, or eleven miles east of Chama. Colo. It has reached an altitude of approximately ' ' 10.000 feet. About six miles remain to be constructed in order to reach the r j summit. When completed the pass will j be 13.000 feet high, which will be the 1 highest automobile road in the state ■ and also one of the most scenic. There l- are a few inchea of snow already on * the pass at the present time. ' 1 he east side also requires six or eight miles of construction to reach * the top. On the east side Whiskey r creek runs near the route, hence the ’’ name given to the pass. Ultimately the ’ mountain highway will shorten the roundabout mute between Trinidad 1 and San Luis to slightly over fifty * miles. A good road exists at present * from Trinidad to Stonewall, the construction on the east side starting | I from this point. A motor road also connects Stonewall with la Vela. Resident Highway Engineer W. J. Walsh, of this city, supervised this | year the construction of the first eleven miles between Chama and the present terminus of the scenic route, completing this stretch about two months ago. The state has turned the work over to Costilla county, which is mainl taining a small crew. Local engineers do not know just what appropriation will be made next year toward completion of the project. Another point not decided is whether to tunnel 1 through a peak near the summit or i surround it. If It is tunneled, the ali titude is decreased only 400 feet. > Though attaining a high altitude in ' a few miles, the grade is easy. Most > of it required heavy blasting, as solid * rock is encountered as soon as the I mountain is reached This makes the i highway fairly permanent, with post Bible exceptions of slides and snow. Valley residents will particularly ap--1 predate the new highway, as en route the automobtlist passes through the ■ old towns of San Pablo and Chama. i which are quaint and picturesque, r Farther east is the estate of the Sala- * zar family, also beautifully located. * Salazar creek meanders down the » western side, productive farms lying l on each side of ?ne stream. The aur tumn foliage at present makes the trip I impressive. However. It is not advis- * able to try to negotiate the last half- : ; mile beyond the construction camp ) Some highway maps show that Chama lies a distance below San Luis but the motorist is advised to turn east on * the first highway he reaches after en- -' tering the upper section of San Luis.
