There are
1,038 mi
from Cheyenne, WY to San Marcos, TX
That's the driving distance. It would take 18 hours 56 mins to go from Cheyenne, Wyoming to San Marcos, Texas.
The flight distance (direct flight from Cheyenne, WY to San Marcos, TX) is 867.93 mi.
1,038 mi = 1,670.33 kms