There are
778 mi
from Sioux City, IA to Romulus, MI
That's the driving distance. It would take 14 hours 16 mins to go from Sioux City, Iowa to Romulus, Michigan.
The flight distance (direct flight from Sioux City, IA to Romulus, MI) is 663.52 mi.
778 mi = 1,251.99 kms