There are
1,016 mi
from Thornton, CO to San Jacinto, CA
That's the driving distance. It would take 17 hours 46 mins to go from Thornton, Colorado to San Jacinto, California.
The flight distance (direct flight from Thornton, CO to San Jacinto, CA) is 783.93 mi.
1,016 mi = 1.61 kms