There are
996 mi
from Thornton, CO to Oconomowoc, WI
That's the driving distance. It would take 18 hours 2 mins to go from Thornton, Colorado to Oconomowoc, Wisconsin.
The flight distance (direct flight from Thornton, CO to Oconomowoc, WI) is 879.91 mi.
996 mi = 1,602.15 kms