There is currently no indoor skiing in North America. There was supposed to be one in the Meadowlands, NJ(called Xanadu, now called Big Snow America) outside of NYC, but it's been delayed for years due to problems with investors. The indoor snow facility is fully built, but the project as a whole (mall/stadiums/theme park) is still delayed. The UK has the most places the closest together, Holland has the biggest and best.
Someday hopefully you can road trip around the US and ski places like these: