There are
1,110 mi
from Thornton, CO to Susanville, CA
That's the driving distance. It would take 18 hours 44 mins to go from Thornton, Colorado to Susanville, California.
The flight distance (direct flight from Thornton, CO to Susanville, CA) is 828.02 mi.
1,110 mi = 1.61 kms