There are
1,006 mi
from Thornton, CO to Deerfield, IL
That's the driving distance. It would take 17 hours 50 mins to go from Thornton, Colorado to Deerfield, Illinois.
The flight distance (direct flight from Thornton, CO to Deerfield, IL) is 905.31 mi.
1,006 mi = 1.61 kms