There are
1,735 mi
from Walnut Creek, CA to San Marcos, TX
That's the driving distance. It would take 1 day 6 hours to go from Walnut Creek, California to San Marcos, Texas.
The flight distance (direct flight from Walnut Creek, CA to San Marcos, TX) is 1,484.98 mi.
1,735 mi = 2,792.61 kms