There are
2,656 mi
from San Mateo, CA to Johnstown, PA
That's the driving distance. It would take 1 day 22 hours to go from San Mateo, California to Johnstown, Pennsylvania.
The flight distance (direct flight from San Mateo, CA to Johnstown, PA) is 2,316.87 mi.
2,656 mi = 3.22 kms