Filming Location

Just watched this movie for the first time today. I found it interesting that the story takes place in Pennsylvania. As a result, I came on to IMDb to find out exactly where since I am a PA resident. Seems that the entire movie was filmed in and around Atlanta, GA. Obviously, the environment (trees and fauna) are not that of the northeast, why dont the film makers just say that the locale is in Georgia to begin with? You're just setting yourself up to movie goofs if you happen to capture a palm tree, spanish moss etc... in your location shots.