There are
1,924 mi
from Decatur, IL to Walnut, CA
That's the driving distance. It would take 1 day 9 hours to go from Decatur, Illinois to Walnut, California.
The flight distance (direct flight from Decatur, IL to Walnut, CA) is 1,638.77 mi.
1,924 mi = 3,095.79 kms