Not planned
This site is built around a question that matters where resorts make their own winter: when does it get cold enough to blow snow, and how long after that do they open? Somewhere with real snowfall, the answer may be dull. The resort opens when it snows. Whether any of this is worth having for the Rockies, the East or anywhere else is genuinely an open question.
We need somebody to help find opening dates, closing dates, and where the two can be told apart, the pre-season opening versus the full one. That mostly means trolling their Facebook feeds by hand. Sometimes the websites have it. Minnesota shows what a region looks like once it is filled in.
If you want this for your mountains, say so and say what would make it useful. Email eazydp@gmail.com. Dates for resorts already listed are just as welcome.