There are
1,745 mi
from Simi Valley, CA to Watertown, SD
That's the driving distance. It would take 1 day 6 hours to go from Simi Valley, California to Watertown, South Dakota.
The flight distance (direct flight from Simi Valley, CA to Watertown, SD) is 1,360.99 mi.
1,745 mi = 1.61 kms