There are
853 mi
from Thornton, CO to Buckeye, AZ
That's the driving distance. It would take 16 hours 9 mins to go from Thornton, Colorado to Buckeye, Arizona.
The flight distance (direct flight from Thornton, CO to Buckeye, AZ) is 615.75 mi.
853 mi = 1,372.80 kms