There are
985 mi
from Gresham, OR to Monrovia, CA
That's the driving distance. It would take 18 hours 40 mins to go from Gresham, Oregon to Monrovia, California.
The flight distance (direct flight from Gresham, OR to Monrovia, CA) is 818.69 mi.
985 mi = 1,585.59 kms