Lisa P will remember this. A few years ago a woman stopped at a highway service area to use the ladies room. An employee of the restaurant followed her into the bathroom. An on duty state police officer was standing right in the lobby. He followed her anyhow. Sadly the officer wasn't able to get to her in time.
I think of her ever time I travel anywhere alone. If I'm not able to carry, I try to keep pepper spray on my keychain, but be sure you know the laws so you don't wind up being prosecuted. Believe it or not, bug spray works very well as a defensive agent.