Really, you can't? How about the fact that for hundreds of years an ever increasing swarm of the most successfull predators of all (human beings)were hell bent to eradicate them. We took out quite a list of species in the east including elk,grey moose, buffalo and almost the whitetail and these are just a few of the species that were eliminated not on purpose but just in the wake of the human expansion. Mountain lions were hunted,poisoned and shot on sight by anybody and everybody just to get rid of them.And BTW, PA is one of the most populated states in the U.S. with 268 people per sqare mile according to the 1999census. You have 12 MILLION people, more than 45,000 miles of state highway alone and yet less than 45,000 square miles in area. A mountain lions range is over 150 sqaure miles. The experts will tell you that the cougars were gone by the mid to late 1800's when the human population was tiny compared to today. I think its pretty easy to "imagine" that they just aren't here any more. Just like dozens of other species that were here when the pilgrims landed butnow are gone.