There are
1,546 mi
from San Marcos, CA to San Benito, TX
That's the driving distance. It would take 1 day 2 hours to go from San Marcos, California to San Benito, Texas.
The flight distance (direct flight from San Marcos, CA to San Benito, TX) is 1,266.58 mi.
1,546 mi = 1.61 kms