Dividing Classic and Modern Horror

[Spooked]

I've had my Horror Blu-rays organized by 'Classic' and 'Modern' genres for quite awhile now, but as I sat down to re-organize a shelf last night, I noticed that I (without conscious thought) drew the dividing line at the year 1978. I guess I consider John Carpenter's Halloween to be 'Modern Horror', while movies like Rosemary's Baby and The Exorcist could be grouped into 'Classic Horror' along with the Universal and Hammer Monster films.

But then, I realized that The Texas Chainsaw Massacre would be considered 'Classic' by this system, and that didn't seem quite right. And what about The Omen? Classic or Modern?

It's kind of interesting to dive in to - I thought I'd see what some people on here thought. Where would you draw the line? And how do you classify your own Horror collection?