Glen Rio, Texas
Glen Rio is either the first town in New Mexico or the last town in Texas as the state line runs right through the middle. The small town died when I40 bypassed it. It only ever had a motel/cafe, a post office, and a gas station and there's not much left of any of them now.
When you are through visiting the ruins you can turn around and go back to Exit 1 in Texas or, if you have sufficient clearance, you can continue on for a couple of miles of bad desert road and rejoin I40 in New Mexico. Part of this dirt road used to be a paved portion of 66 but the New Mexico side pulled up the pavement some years back because the maintenance cost was too high. Sigh! Another piece of Americana gone.