Post Your Region and the most difficult trail you have there.
New Hampshire: Huntington Ravine Trail
https://sectionhiker.com/great-hikes-mt-washington-and-the-huntington-ravine-trail/
Not the most difficult in Montana, but the most difficult I've personally done.
http://www.summitpost.org/black-mountain/152348
>>1058049
I've never been out West, but I will not go without backpacking in Absaroka. The sacred homeland of the Crow is supposed to be a paradise.
>>1058053
It's pretty unreal man, and way less crowded than Glacier or Yellowstone
>>1058045
Kentucky. The most difficult hikes aren't on trails.