Patently untrue, but I take your meaning.

Of course they were found virtually everywhere before we screwed up the neighborhood.
I would be interested to know where these bears are migrating from, how far, and if the places they're that they're showing up in are recent developments.
Bears do tend to wander, partially due to food supply. Grew up in Baltimore myself. In the late 60's I found a good sizes bear, 2-300lbs, dead in a farmers field about 100yds from the Big Gunpowder River at Rt 40. Seems some redneck at the nearby truckstop saw it crossing Rt40 and just had to shoot it. A few years later a friend of mine came across a black bear while training his bird dog in Baltimore Co at the Pa line near I 83. I suspect that these were not all that unusual of occurances but that as our population density increases the beasts have fewer chances to stay out of our way.