Winter brings a frosty, and icy, new robe to many national parks. The biting cold against the snowy settings can be magical, as these photos show.

Since 1966, national scenic and historic trails have been an American priority. They traverse mountains, canyons, forests, and grasslands across the country, crossing creeks and rivers and skirting lakes. These narrow corridors through the wilderness provide recreation and protect historic resources while conserving natural features. There are many physical, emotional, and logistical requirements for these trips, and winter is the perfect season to get in shape and plan for a long walk. Here’s a quick look at a few of these trails to help you plan a trip.

Rocky Mountain National Park, with its sky-scraping peaks, deep valleys gouged out of the landscape by creeks and rivers fueled by snowmelt, and forests thick with conifers and dappled with aspens, is a hiker's dreamscape. Though there are only 355 miles of marked trails, far fewer than Great Smoky Mountains, Yellowstone, Glacier, and many other national parks, Rocky Mountain "hikes" much bigger than it seems.

Though just a mile in length, short by most national park trails, the Crater Trail at Rocky Mountain National Park has turned into a problem due to erosion, its crossing of an archaeological site, and its passage through an area for bighorn lambing. As a result, park officials are proposing to permanently close the trail and restore that landscape.