To help you out, I put the information into mapquest.com. It is approximately estimated that driving from Niagara falls and Philadelphia will take 7 hours. If you would like more details on this here is the map quest site.
http://www.mapquest.com/maps?1c=Niagara+Falls&1s=NY&2c=Philadelphia&2s=PA
About 420 road miles.
The driving distance between Buffalo, NY and Niagara Falls, NY is about 20 miles
414 miles to the New York side of the falls.
The driving distance is approximately 400 road miles - about seven hours of driving time.
The driving distance from Mississauga, ON, Canada to Niagara Falls, NY, is 70.2mi / 113km
The distance between Buffalo, NY, and Niagara Falls, NY, is 23.2 miles and will take approximately 31 Minutes of driving time.
The distance between the start point and the destination is 418 miles, and will take approximately 6 hours 51 minutes of driving time.
600
571 miles
457 miles
about 1800 miles
81.3 miles