There are
999 mi
from Thornton, CO to Yucaipa, CA
That's the driving distance. It would take 17 hours 27 mins to go from Thornton, Colorado to Yucaipa, California.
The flight distance (direct flight from Thornton, CO to Yucaipa, CA) is 777.89 mi.
999 mi = 1,606.96 kms