There are
1,635 mi
from Kennewick, WA to Marshalltown, IA
That's the driving distance. It would take 1 day 4 hours to go from Kennewick, Washington to Marshalltown, Iowa.
The flight distance (direct flight from Kennewick, WA to Marshalltown, IA) is 1,325.66 mi.
1,635 mi = 2,630.50 kms