There are a few main ways people can access the Rocky Mountains in winter to go skiing:
1. By driving - Many people drive their own vehicles to the various ski resorts in the Rockies. This can involve long drives from major cities like Denver, Salt Lake City, Calgary, etc. Winter driving conditions can be hazardous at times, so appropriate vehicles, tires, and supplies are recommended.
2. By shuttle/bus - Some resorts offer shuttle buses during ski season from major cities nearby. This can be a convenient option for those who don't want to drive themselves. Shuttles typically operate on a schedule and must be booked in advance.
3. By air - Several of the larger ski resorts in the Rockies have their own airports, or are located near regional airports. People can fly into these airports and then take a shuttle or taxi to the resort. This is a common option for people coming from farther distances.
4. By train - Amtrak operates the Winter Park Express train during ski season that runs between Denver's Union Station and the Winter Park Resort in Colorado. It is a scenic train ride through the Rockies. Some other ski towns are accessible by long-distance train routes.
So in summary, a combination of driving, shuttles/buses, flying, and limited train options are the primary ways people access the Rocky Mountain ski resorts during the winter. The method depends mainly on the distance one is traveling from and personal preference. All of these transportation options can be researched in advance to determine the best and most cost-effective itinerary.
Hope this helps! Let me know if you have any other questions.