From the text of the Wilderness Act:
there shall be no temporary road, no use of motor vehicles, motorized equipment or motorboats, no landing of aircraft, no other form of mechanical transport, and no structure or installation within any such area.
"Mechanical transport" has generally been taken to mean anything with wheels (eg. bicycles). Has there been any ruling about wheelchairs, either explicitly prohibiting or explicitly permitting them?
According to Section 508 (c) of the American with Disabilities Act, Title V,
(1) In general. - Congress reaffirms that nothing in the Wilderness Act [16 U.S.C. 1131 et seq.] is to be construed as prohibiting the use of a wheelchair in a wilderness area by an individual whose disability requires use of a wheelchair, and consistent with the Wilderness Act no agency is required to provide any form of special treatment or accommodation, or to construct any facilities or modify any conditions of lands within a wilderness area in order to facilitate such use.
(2) Definition. - For purposes of paragraph (1), the term "wheelchair" means a device designed solely for use by a mobility-impaired person for locomotion, that is suitable for use in an indoor pedestrian area.
Wheelchairs are not disallowed by the Wilderness Act. They do not have to provide accommodations or a wheelchair in a wilderness area, but they do not disallow their use.
Note: a different version of the act has it as Section 507 (c) but includes the same text.
This document (thank you @csk) further states:
Application of definition of a Wheelchair (per ADA Title V Section 508c; 36 CFR 212.1 and FSM 2353.05): “Designed solely for use by a mobility-impaired person” means that the original design and manufacture of the device was only for the purpose of mobility by a person who has a limitation on their ability to walk. A wheelchair or mobility device, even one that is a battery powered, that meets this definition is allowed anywhere foot travel is allowed even in federally designated Wilderness.
“Suitable for indoor pedestrian use” means the device would be allowed to be used inside a courthouse, the food court of a mall, etc. on the wood, carpeted or tile floors. Also the Architectural Barriers Act Accessibility Standards (ABAAS) standard for clear passage through a gate or a doorway is 36 inches. So will the device fit through? If the answer is “Yes” to all that device is allowed anywhere foot travel is allowed including in federally designated Wilderness.
This would preclude things like something with a 2-stroke engine and outrigger wheels, mainly due to the combustion engine, and possibly if it no longer fits the width requirements. The ADA also states:
The Department also expects that, in most circumstances, people with disabilities using ATVs and other combustion engine-driven devices may be prohibited indoors and in outdoor areas with heavy pedestrian traffic.
Based on that, you would not be allowed a wheelchair with a combustion engine indoors, and therefor it would not be allowed in the wilderness either.
On feasibility and whether this is even of legitimate concern, this account (once again, thank you @csk) is from someone who makes use of a wheelchair in Wilderness areas on a fairly regular basis.
I had left my battery powered wheelchair at home as my manual chair is lightweight and folds nicely into a canoe. It takes the help of my friends to get me over the rough terrain, in and out of my tent and sleeping bag, up the hill to the toilet, and so forth. Whereas in my daily life I often chafe at needing assistance, on a wilderness trip it is simply part of a team effort with a mutual goal of a shared experience and therefore it is worth it to me.
It was not a “wheelchair accessible” area, but as a quadriplegic, I couldn’t have been happier to be there. I was back in wilderness. The part of me I was afraid I had lost had been found. From that point on, I knew I could once again do whatever I set my mind to.
Easy? No. Doable? Evidently so.
It's worth mentioning that many wilderness areas have very convoluted boundaries that provide access to the margins of these areas. Trapper's Lake campground isn't wilderness, nor is the access road, but it is completely surrounded by The Flattops Wilderness, and the lake itself is wilderness. The wilderness area basically starts at the edge of the campsites. So wheelchair access, albeit not very deep, was certainly possible. I had the great fortune to be a camp host there for one summer.
I also did a good bit of ADA type work on behalf of the USFS under contract back in the 90's. This included making access improvements all over Colorado, and trying to get access policy sorted out and somewhat consistent among about 14 different agencies that played a role managing the sundry wild areas of Colorado. I can't promise that somebody from the Denver Water Board or Summit County Fire and Rescue or Federal Marshal's Office won't mistakenly tell you that you shouldn't be in a wilderness area on a wheelchair, But I tried my best.
While the policy position on physical access is explained above, there remains an affirmative duty to provide access to comparable wilderness experiences to all.
Here's an excerpt from Wilderness Accessibility for People with Disabilities: A Report to the President and the Congress of the United States on Section 507(a) of the Americans with Disabilities Act by the National Council on Disability.
BACKGROUND
In 1964 Congress passed the Wilderness Act and established the National Wilderness Preservation System (NWPS). The NWPS is not an independent lands system; rather, it is made up of lands managed by four federal agencies: the U.S. Forest Service, the National Park Service, the U.S. Fish and Wildlife Service, and the Bureau of Land Management.
Congress has sole authority to designate wilderness areas, but the four federal agencies must manage these lands within the parameters specified by the Wilderness Act. As stated in Section 2(a), the purpose of the Wilderness Act is
...to assure that an increasing population, accompanied by expanding settlement and growing mechanization, does not occupy and modify all areas within the United States and its possessions, leaving no lands designated for preservation and protection in their natural condition, it is hereby declared to ...secure for the American people of present and future generations the benefits of an enduring resource of wilderness....
Over the years since its passage, some people have claimed that the Wilderness Act discriminates against the rights of persons with disabilities because it prohibits the use of motorized vehicles, mechanized transport, and other activities within federally designated wilderness areas. Section 4(c) of the Wilderness Act states
Except as specifically provided for in this Act...there shall be no temporary road, no use of motor vehicles, motorized equipment or motorboats, no landing of aircraft, no other form of mechanical transport, and no structure or installation within any such area.
The Wilderness Act was written before the rights of people with disabilities were part of the national debate. Not surprisingly, there is no mention of people with disabilities in the Act. Over time, as people with disabilities began to use the wilderness, the question was raised whether a wheelchair is a mechanical device and therefore prohibited from the NWPS. The four federal agencies responsible for managing the NWPS have responded differently to this question.
In 1990 Congress passed the Americans With Disabilities Act (ADA). The ADA gives civil rights protection to individuals with disabilities similar to those provided to individuals on the basis of race, sex, national origin, and religion. Among other issues, the ADA addresses specific wilderness access in Section 507(c):
(1) In General--Congress reaffirms that nothing in the Wilderness Act is to be construed as prohibiting the use of a wheelchair in a wilderness area by an individual whose disability requires use of a wheelchair, and consistent with the Wilderness Act no agency is required to provide any form of special treatment or accommodation, or to construct any facilities or modify any conditions of lands within a wilderness area to facilitate such use.
(2) Definition--For the purposes of paragraph (1), the term wheelchair means a device designed solely for use by a mobility-impaired person for locomotion, that is suitable for use in an indoor pedestrian area.
The primary purpose of this study is to review the management practices of the four federal agencies that manage the NWPS and to determine whether people with disabilities are able to use and enjoy the NWPS.
