There are
1,251 mi
from Great Falls, MT to South Pasadena, CA
That's the driving distance. It would take 21 hours 5 mins to go from Great Falls, Montana to South Pasadena, California.
The flight distance (direct flight from Great Falls, MT to South Pasadena, CA) is 990.71 mi.
1,251 mi = 2,013.90 kms