There are
1,643 mi
from Harlingen, TX to Simi Valley, CA
That's the driving distance. It would take 1 day 4 hours to go from Harlingen, Texas to Simi Valley, California.
The flight distance (direct flight from Harlingen, TX to Simi Valley, CA) is 1,373.34 mi.
1,643 mi = 2,644.23 kms