The Distance From Me to You by Marina Gessner
The Distance From Me to You by Marina Gessner (pen name of Nina de Gramont) tells the story of McKenna, the protagonist of the novel, who decides to hike the entire length of the Appalachian Trail after hearing that her dad did the same. She had originally planned to hike with a friend, but when that friend mysteriously pulls out of the arrangement, McKenna is left by herself to survive in the wilderness. Then she meets Sam, who has taken to the Appalachian Trail to escape his troubled family.