There are
1,923 mi
from Dekalb, IL to Montclair, CA
That's the driving distance. It would take 1 day 9 hours to go from Dekalb, Illinois to Montclair, California.
The flight distance (direct flight from Dekalb, IL to Montclair, CA) is 1,656.95 mi.
1,923 mi = 3,094.07 kms