There are
2,685 mi
from Diamond Bar, CA to Lansdowne, PA
That's the driving distance. It would take 1 day 23 hours to go from Diamond Bar, California to Lansdowne, Pennsylvania.
The flight distance (direct flight from Diamond Bar, CA to Lansdowne, PA) is 2,360.35 mi.
2,685 mi = 4,320.90 kms