There are
2,030 mi
from St Charles, MO to Piedmont, CA
That's the driving distance. It would take 1 day 11 hours to go from St Charles, Missouri to Piedmont, California.
The flight distance (direct flight from St Charles, MO to Piedmont, CA) is 1,712.45 mi.
2,030 mi = 3,267.28 kms