There are
647 mi
from St Charles, MO to Seagoville, TX
That's the driving distance. It would take 12 hours 9 mins to go from St Charles, Missouri to Seagoville, Texas.
The flight distance (direct flight from St Charles, MO to Seagoville, TX) is 542.67 mi.
647 mi = 1,041.42 kms