The Mahoosuc Notch area is commonly known as the "hardest mile on the AT". The Appalachian Trail traverses many miles, many mountains, and many states, but this rocky section of the trail in Maine has been crowned the most difficult. The Mahoosuc Arm section stretches another mile or so up to that high point and includes a pretty rough section of trail, itself. Don't expect to do a lot of running for this stint of the Appalachian Trail!