There are
1,707 mi
from Bethlehem, PA to Thornton, CO
That's the driving distance. It would take 1 day 6 hours to go from Bethlehem, Pennsylvania to Thornton, Colorado.
The flight distance (direct flight from Bethlehem, PA to Thornton, CO) is 1,554.58 mi.
1,707 mi = 1.61 kms