http://www.dnr.state.md.us/naturalresource/fall2007/lions.pdfThis link best describes the eastern cougar/mountain lion population. The fact that so many people see "black" mountain lions to me shows it's that much more unlikely they are seeing mountain lions as a black mountain lion has NEVER been documented in North America. Even back in the colonial days when 1,000's were killed.
In the end it is a very simple math problem. Florida has roughly 100-120 cougars in the wild and has on average, 15-20 of them killed on the road each year. Yet, the rest of the eastern United States has 1 killed every decade and those usually can be tracked back to being a released pet or a long wandering male from far out west.
I hate to break it to people, wild reproducing mountain lions don't exists in the eastern United States. They died off when the whitetail deer almost went extinct(their main food) and the woods were all logged and burned in the late 1800's.