There are
1,880 mi
from Kennewick, WA to St Charles, MO
That's the driving distance. It would take 1 day 8 hours to go from Kennewick, Washington to St Charles, Missouri.
The flight distance (direct flight from Kennewick, WA to St Charles, MO) is 1,535.74 mi.
1,880 mi = 3,026.17 kms