Backpacker magazine wants you to know that it's almost totally safe.
When we did five days in the Smokies last spring, we met a female hiker who was through-hiking the AT alone. She seemed to be having great fun, and is now getting close to finished according to her occasional online updates. Nothing she's written suggests that she's had even a moment's trouble from anyone. But that's an anecdote: Backpacker has the statistics.