America has 62 National Parks.  
https://en.wikipedia.org/wiki/List_of_national_parks_of_the_United_States

I have visited about half.  My lifetime pass resides in my wallet, and many of the visits have been spur of the moment while on cross country drives.  Sometime in the early 80s I took the tele skis to Shenandoah.  There are 25 miles or so of the skyline drive that are plowed in winter, going south from Thornton Gap, where rt. 211 crosses.  There are lots of opportunities, Big Meadows, white oak canyon fire road, Hawksbill fire road, even skyline drive itself.  Now my list is 12, including, Denali, Yellowstone, Yosemite, Glacier, Crater Lake, Black Canyon of the Gunnison, even Cayahoga Valley, OH.  The parks are very different in winter.  At a February meeting at Big Sky, some friends and I played hookey one day and cross country skied in Yellowstone.  A snowcat  brought us from West Yellowstone, MT and dropped us off at a trail head 6 miles from Old Faithful.  Keeping a reasonable pace we got there shortly before an eruption, a catered lunch, and a snowcat visit to several of the thermal hot springs.  It was a warm sunny day.  Light and shadow were so sharply different that I almost skied into the south end of a northbound elk in deep shade that I didn't even see.  

Denis, I'm so glad that you keep posting here even though you have moved out west. Your posts are always interesting. I wish you a speedy recovery from your recent hip replacement.

Here's a short doc on skiing National Parks

https://www.youtube.com/watch?v=AMKPEuuZaA8&has_verified=1

Snowshoeing with my wife in Grand Teton NP, late Feb 2020

Thanks Camp and Jim.  Great stuff.