 The name " Railroad Flat " originates from the Yosemite Valley Railroad , which once travelled up Merced River Canyon into Yosemite Valley . The old railroad grade still exists , and is now the site of a public trail . Many other trails lead throughout the Merced River watershed , notably the John Muir Trail , which starts near Happy Isles and climbs the Giant Staircase , past Vernal and Nevada Falls , into Little Yosemite Valley and north along Sunrise Creek to join the Pacific Crest Trail near Tuolumne Meadows . Trails also follow the river through Little Yosemite Valley to the headwaters area , and along Illilouette , Bridalveil , Yosemite , Alder and <unk> Creeks , and the lower South Fork of the Merced River . There are no trails along some segments , including the lower Bridalveil Creek , upper South Fork , and specifically Tenaya Canyon , which is extremely dangerous . 
