There are
2,682 mi
from San Marcos, CA to Coatesville, PA
That's the driving distance. It would take 2 days to go from San Marcos, California to Coatesville, Pennsylvania.
The flight distance (direct flight from San Marcos, CA to Coatesville, PA) is 2,321.05 mi.
2,682 mi = 4,316.22 kms