Overview:The Highline Trail in Glacier National Park is an extremely popular hike hosting more than 3 million visitors every year. However, don't let the popularity fool you into thinking it's a breeze. The Highline Trail is one of the toughest in America, with spectacular views and ample wildlife. If you plan on visiting Glacier National Park, do so ASAP! Scientists say that by 2030, the glaciers would have melted due to climate change and forest fires.