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The John Muir Trail (JMT) is a long-distance trail in the Sierra Nevada mountain range of California, running 211 miles (340 km) between the northern terminus at Happy Isles in Yosemite Valley and the southern terminus located on the summit of Mount Whitney. The only other points where the trail passes near a road is in Tuolumne Meadows in Yosemite National Park  and at Red's Meadow near Devil's Postpile National Monument. For about 160 miles (260 km), the trail, named for naturalist John Muir, follows the same footpath as the longer Pacific Crest Trail. It also passes through Kings Canyon National Park and Sequoia National Park.
The official length of the JMT, as stated by the United States Geological Survey (USGS), is 211 miles (340 km). From its northern terminus in Yosemite Valley, the trail runs northeast, passing south of Half Dome and then on to Tuolumne Meadows. From Tuolumne Meadows the trail turns south, running parallel to the main range of the Sierra Nevada, through Yosemite National Park, Inyo and Sierra national forests (including the John Muir and Ansel Adams wilderness areas), passing through Devils Postpile National Monument, through Kings Canyon National Park, and ending on Mount Whitney in Sequoia National Park.
From the southern terminus of the John Muir Trail at the summit of Mount Whitney, an additional 11-mile (18 km) hike on the Mount Whitney Trail is required to reach the nearest trailhead at Whitney Portal, thus making an end-to-end traverse of the trail effectively 220 miles (350 km).
With the exception of the first 9 miles (14 km) at the northern end climbing out of Yosemite Valley, the elevation of the John Muir Trail seldom dips below 8,000 feet (2,400 m). The trail crosses six passes in excess of 11,000 feet (3,400 m); from north to south, they are: Donohue Pass, Muir Pass, Mather Pass, Pinchot Pass, Glen Pass, and Forester Pass (the highest, at 13,153 feet (4,009 m)).
When the length of the John Muir Trail was calculated by the USGS, elevation gain and loss was not taken into consideration. It is estimated[who?] that, when hiking north to south, the amount of ascent of the JMT is just over 46,000 feet (14,000 m) and the total descent is just over 38,000 feet (12,000 m), for a total of about 84,000 feet (26,000 m), or almost 16 miles (26 km); however, this does not mean the total length is increased by 16 miles (26 km).
The idea of the trail along the backbone of the High Sierra originated with Theodore Solomons. Solomons later recalled that the concept originated in his adolescence. "The idea of a crest-parallel trail came to me one day while herding my uncle's cattle in an immense unfenced alfalfa field near Fresno. It was 1884 and I was 14."  He began advocating construction of the trail shortly after the Sierra Club was founded in 1892. John Muir was a founding member and first president of the Sierra Club. Solomons explored the area now known as the Evolution Basin, and traveled extensively thoughout the High Sierra, exploring possible trail routes. Joseph N. LeConte took up the cause in 1898 and the proposed trail was originally called the High Sierra Trail, although that name was later given to an east-west trail. LeConte spent years exploring the canyons and passes of the Kings River and Kern River, and climbing peaks along the proposed trail. Along with James S. Hutchinson and Duncan McDuffie, he pioneered a high mountain route in 1908 from Yosemite National Park to Kings Canyon, roughly along the route of the modern John Muir Trail. In 28 days, they completed a trip of 228 miles through the high mountains, including several previously unexplored sections. In 1914, the Sierra Club appointed a committee to cooperate with the State of California to begin construction of the trail. John Muir died later that year, and the proposed trail was renamed in his honor.
Construction of the John Muir Trail began a year after Muir's death in 1915 with a $10,000 grant from the California legislature. State Engineer Wilbut F. McClure was responsible for selecting the final route. He secured the cooperation of the U.S. Forest Service which managed and supervised much of the actual construction. The state legislature made additional appropriations of $10,000 each in 1917, 1925, 1927 and 1929.
After the Depression began, assistance from the California state government came to an end, and there were still two difficult sections yet to be completed. One was the connection from the Kings River to the Kern River over Forester Pass 13,153 feet (4009 m), which was completed in 1932 through joint effort between the Forest Service and the National Park Service. In 1938, the final section up Palisade Creek at the headwaters of the Middle Fork of the Kings River and over Mather Pass by the "Golden Staircase" to the headwaters of the South Fork of the Kings River was completed in 1938 by the Forest Service. Shortly after, this section was incorporated into newly-created Kings Canyon National Park. The entire project had taken 46 years to complete.
William Colby, the first secretary of the Sierra Club, called the finished trail "a most appropriate memorial to John Muir, who spent many of the best years of his life exploring the region which it will make accessible." 
The primary hiking season is usually from July through September, though snow may linger on the higher passes well into August following heavy snow years. Early season hikers—including Pacific Crest Trail thru-hikers headed north for Canada -- have to contend not only with the snowpack and icy slopes near the passes, but with streams swollen with snowmelt. Trail conditions are less demanding later in the season after the snowmelt concludes, and the weather generally remains pleasant for hiking through September.
Weather during the hiking season is generally sunny and dry, but afternoon thunderstorms are not uncommon. The trail is used primarily by backpackers and dayhikers, but also by runners, trail riders, and pack trains. Backpackers travelling at a generous pace usually complete the trail within three weeks.
A permit is required to hike the JMT, which is obtained from the national park or forest where the hiker begins the hike. This single permit is valid for the entire hike. Permits can be hard to obtain for JMT thru-hikers. Both ends of the JMT, Yosemite and Whitney Portal have a lottery for wilderness permits. In addition, in Yosemite hikers face competition with other backpackers simply wanting to camp overnight while hiking Half Dome or to Tuolumne Meadows. Backpackers entering the Sierra backcountry on multi-day trips are generally required to carry their food in approved hard-sided storage containers known as bear canisters to protect their food and other scented items from theft by black bears, which are common in the region.
About 75-90 percent of hikers hike north to south, from Yosemite Valley to Mt. Whitney. There are advantages to starting in Yosemite Valley and hiking south. Although there is a significant net altitude gain this way, starting at a lower altitude allows the hiker time to acclimate to the elevations of the trail rather than immediately having to tackle a 6,000-foot (1,800 m) climb to the summit of Mount Whitney. In addition, there are several resupply points convenient to the JMT during its northern half (Tuolumne Meadows, Reds Meadow, Vermillion Valley Resort, Muir Trail Ranch), allowing the hiker to carry a lighter food load early in the hike and also to exit the trail easily if problems arise. The southern half of the JMT is more remote and generally higher in elevation, thus making it more appropriate for the second half of the hike when maximum conditioning has been attained.