Yosemite Valley and the Merced River. Credit: Wikimedia/By King of Hearts - Own work, CC BY-SA 3.0. Some rights reserved.
On September 2 1867, a 29-year old Scottish immigrant called John Muir sat alone in an oak wood on the shore of the Ohio River, a pocket map spread in front of him, his forefinger tracing an arc through the deep South of Kentucky, Tennessee, North Carolina and Georgia, and finally pausing along the Florida Gulf coast a thousand miles away. He planned to walk there.
