No sub-alpine regions exist between Mount Rogers in Virginia and Mount Greylock in Massachusetts, mainly because the trail stays below 3,000 feet (910 m) from Shenandoah National Park in Virginia to Mount Greylock. Mount Greylock, however, has a large subalpine region, the only such forest in Massachusetts, extending down to 3,000 feet (910 m), which in the south would be far from the sub-alpine cutoff. This is especially low because Greylock is exposed to prevailing westerly winds, as its summit rises 1,000 feet (300 m) higher than any other peak in Massachusetts. Further north, several peaks in Vermont reach into the sub-alpine zone, the bottom of which steadily descends, so that by the White Mountains in New Hampshire, it often occurs well below 3,000 feet (910 m). At Mount Moosilauke, which reaches to 4,802 feet (1,464 m), the first alpine environment on the trail is reached, where only thin, sporadic flora is interspersed with bare rocks. Between the two regions is the krummholz region, where stunted trees grow with their branches oriented away from the winter's prevailing northwest wind, thus giving the appearance of flags (they are often called "flag trees"). This region resembles lowland terrain hundreds of miles north in Canada. It also contains many endangered and threatened species. The trail has been rerouted over New Hampshire's Presidential Range so the Appalachian Mountain Club can protect certain plant life. The alpine cutoff in the Whites is generally between 4,200 and 4,800 feet (1,500 m). Mountains traversed by the AT above treeline include Mount Moosilauke, several miles along the Franconia Range, and the Presidential Range. In the Presidentials, the trail climbs as high as 6,288 feet (1,917 m) on Mount Washington and spends about 13 miles (21 km) continuously above treeline, in the largest alpine environment in the United States east of the Rocky Mountains.
Diagram of the Appalachian Mountain system
In Maine, the trail extends into even harsher environments, and sub-alpine and alpine growth descends to lower elevations. Alpine growth in the state ranges from around 2,500 feet (760 m) in the Mahoosuc Range to below 1,000 feet (300 m) in parts of the Hundred-Mile Wilderness, where nearly every area higher than 1,000 feet (300 m) is evergreen forest. These forests include more species of evergreen, as well. In addition to the white pine, spruce and hemlock prevalent further south, Maine has many cedar trees along the trail. Near the northern terminus, there are even some tamarack (larch), a coniferous, pine-needled deciduous tree, which provides displays of yellow in the late fall after the birches and maples have gone bare. The hemlocks in Maine are also notable, as the woolly adelgid, which has ravaged populations further south, has not come into the state yet, and may be unable to make it so far north due to the cold climate.
Maine also has several alpine regions. In addition to several areas of the Mahoosuc Range, the Baldpates and Old Blue in southern Maine have alpine characteristics despite elevations below 4,000 feet (1,200 m). Saddleback Mountain and Mount Bigelow, further north, each only extend a bit above 4,000 feet (1,200 m), but have long alpine areas, with no tree growth on the summits and unobstructed views on clear days. From Mount Bigelow, the trail extends for 150 miles (240 km) with only a small area of alpine growth around 3,500 feet (1,100 m) on the summit of White Cap Mountain. Mount Katahdin, the second largest alpine environment in the eastern United States, has several square miles of alpine area on the flat "table land" summit as well as the cliffs and aretes leading up to it. Treeline on Mount Katahdin is only around 3,500 feet (1,100 m). This elevation in Massachusetts would barely be a sub-alpine region, and, south of Virginia, consists of lowland forest. This illustrates the drastic change in climate over 2,000 miles (3,200 km).
Despite the alpine environments well below 5,000 feet (1,500 m) in New Hampshire and Maine, some higher places further south are not alpine. Examples include Wayah Bald in North Carolina 5,342 feet (1,628 m) and Clingman's Dome in Great Smoky Mountains National Park 6,643 feet (2,025 m).
Hiking the trail
As the Appalachian Trail was explicitly designed to be hiked, it includes resources to facilitate hikers. Some are common to trails throughout North America, while some are unique to the Appalachian Trail. The trail is much more frequently hiked south to north (i.e. Georgia to Maine) than vice versa. Hikers typically begin in March or April and finish in late summer or early to late fall of that particular year.
Throughout its length, the AT is marked by 2-by-6-inch (5-by-15-cm) white paint blazes. Side trails to shelters, viewpoints and parking areas use similarly shaped blue blazes. In past years, some sections of the trail also used metal diamond markers with the AT logo, few of which survive.
Lodging and camping
An information house in Boiling Springs, Pennsylvania
The trail has more than 250 shelters and campsites available for hikers. The shelters, sometimes called lean-tos (in Maine, Massachusetts, and Connecticut), huts (in Shenandoah National Park) or Adirondack shelters, are generally open, three-walled structures with a wooden floor, although some shelters are much more complex in structure. Shelters are usually spaced a day's hike or less apart, most often near a water source (which may be dry) and with a privy. They generally have spaces for tent sites in the vicinity. the Appalachian Mountain Club (AMC) operated a system of eight huts along 56 miles of New Hampshire's White Mountains. These huts are significantly larger than standard trail shelters and offer full-service lodging and meals during the summer months. The Fontana Dam Shelter in Maine, is more commonly referred to as the Fontana Hilton because of amenities (eg. flush toilets) and its proximity to an all-you-can-eat buffet and post office. Several AMC huts have an extended self-service season during the fall, with two extending self-service season through the winter and spring. The Potomac Appalachian Trail Club maintains trail cabins, shelters, and huts throughout the Shenandoah region of Virginia.
Shelters are generally maintained by local volunteers. Almost all shelters have one or more pre-hung food hangers (generally consisting of a short nylon cord with an upside-down tuna can suspended halfway down its length) where hikers can hang their food bags to keep them out of the reach of rodents. In hiker lingo, these are sometimes called "mouse trapezes."
In addition to official shelters, many people offer their homes, places of business, or inns to accommodate AT hikers. One example is the Little Lyford Pond camps maintained by the Appalachian Mountain Club. Inns are more common in sections of the trail that coincide with national parks, most notably Virginia's Shenandoah National Park.
The trail crosses many roads, thus providing ample opportunity for hikers to hitchhike into town for food and other supplies. Many trail towns are accustomed to hikers passing through, and thus many have hotels and hiker-oriented accommodations. Some of the most well-known trail towns are Hot Springs, North Carolina, Erwin, Tennessee, Damascus, Virginia, Harpers Ferry, West Virginia, Duncannon, Pennsylvania, Port Clinton, Pennsylvania, Hanover, New Hampshire, and Monson, Maine. In the areas of the trail closer to trail towns, many hikers have experienced what is sometimes called "trail magic," or assistance from strangers through kind actions, gifts, and other forms of encouragement. Trail magic is sometimes done anonymously. In other instances, persons have provided food and cooked for hikers at a campsite.
Introduction, History | Extensions, Animals, Plants
Topography, Hiking the trail, Navigation, Lodging and camping, Trail towns
Hazards, Trail Completion | The Route and the States