There are
1,855 mi
from San Marcos, CA to Hazelwood, MO
That's the driving distance. It would take 1 day 8 hours to go from San Marcos, California to Hazelwood, Missouri.
The flight distance (direct flight from San Marcos, CA to Hazelwood, MO) is 1,542.09 mi.
1,855 mi = 1.61 kms