Kind of interesting on the photo with all the old road signs on the wall, (the one warning of dangerous slow children) that apparently the Automobile Club of Southern California reached far throughout the southwest. The Lincoln Highway sign would have been posted in Nevada near the Utah state line and the sign above and to the right of that would have been hung in southwestern New Mexico. A lot of these would have been tough to read and you'd probably have to stop to read the directional signs.
I wonder where they all went! Tough pieces to find that's for sure.