Pacific Crest Trail
The route was first explored in the 1930s by teams from the YMCA. Clinton Clarke and Warren Rogers lobbied the federal government to provide a corridor. The PCT was eventually designated one of the first scenic trails in the National Trails System authorized by Congress in 1968, and was dedicated in 1993.
Useful information about the trail is provided by the Pacific Crest Trail Association 
To understand the trail it has been divided in many guidebooks into 3 sectors.
Southern California (Mexico-Tuolumne Meadows, Yosemite)
Northern California (Tuolumne Meadows, Yosemite-Oregon)
Pacific Northwest (Oregon-Canada)
Most hikers travel South to North, but a few start from Canada.
There are many sections of the trail that can be hiked individually, but the PCT departs from the Mexican border near the small town of Campo, and ends at Monument 78 on the Canadian border.