There are
1,599 mi
from St Charles, MO to Boise, ID
That's the driving distance. It would take 1 day 3 hours to go from St Charles, Missouri to Boise, Idaho.
The flight distance (direct flight from St Charles, MO to Boise, ID) is 1,372.27 mi.
1,599 mi = 2,573.51 kms