There are
1,725 mi
from Longmont, CO to Phoenixville, PA
That's the driving distance. It would take 1 day 7 hours to go from Longmont, Colorado to Phoenixville, Pennsylvania.
The flight distance (direct flight from Longmont, CO to Phoenixville, PA) is 1,555.27 mi.
1,725 mi = 1.61 kms