If you are brave enough and in good health, must try the top 3 hiking trails in the USA, absolutely a challenge for backpackers:
The hardest hiking - Continental Divide Trail
4988 kilometers long, it passes through New Mexico, Montana, Wyoming and Colorado, nearly no supply points, and no enough guideposts, more serious is that you’ll meet with frozen snow, thunderstorm as well as grizzly bears, but in Bob Marshall Wilderness you may enjoy the most spectacular Wilderness Scenery.
The hardest hiking - Continental Divide Trail
4988 kilometers long, it passes through New Mexico, Montana, Wyoming and Colorado, nearly no supply points, and no enough guideposts, more serious is that you’ll meet with frozen snow, thunderstorm as well as grizzly bears, but in Bob Marshall Wilderness you may enjoy the most spectacular Wilderness Scenery.
The coldest hiking trip -- The Ice Age Trail
About 1931 kilometers in Winconsin, you may be here in search of mammoth footsteps, near the Milwaukee river have many geological features after the ice age: drift boulder, potholes etc., some temporary shelters can also be found here. So far only a few of backpackers have passed through the whole trail.
The oldest trail– the long trail
The most ancient long-distance trails with a history of about 90 years, located in Vermont, 438 kilometers long, but there is a rest room every 15 kilometers or so, the best season is from the end of Sep to early Oct.