Once you get past Abilene or San Angelo you're getting into the eastern reach of the Chihuahuan Desert, so around 4 hours. Some maps put it west of the Pecos bu

Once you get past Abilene or San Angelo you're getting into the eastern reach of the Chihuahuan Desert, so around 4 hours. Some maps put it west of the Pecos but that's not the official line, to be fair different maps seem to put it in different places.