There are
1,720 mi
from Thornton, CO to Phoenixville, PA
That's the driving distance. It would take 1 day 6 hours to go from Thornton, Colorado to Phoenixville, Pennsylvania.
The flight distance (direct flight from Thornton, CO to Phoenixville, PA) is 1,552.05 mi.
1,720 mi = 1.61 kms