There are
1,994 mi
from San Marcos, CA to Sycamore, IL
That's the driving distance. It would take 1 day 10 hours to go from San Marcos, California to Sycamore, Illinois.
The flight distance (direct flight from San Marcos, CA to Sycamore, IL) is 1,665.51 mi.
1,994 mi = 1.61 kms