Miles between Thornton, CO and Alton, IL

There are
857 mi
from Thornton, CO to Alton, IL

That's the driving distance. It would take 15 hours 11 mins to go from Thornton, Colorado to Alton, Illinois.

The flight distance (direct flight from Thornton, CO to Alton, IL) is 791.73 mi.

857 mi = 1,378.85 kms