In promoting the development of the John Muir Trail and in fostering the use of High Sierra trails, generally, the Sierra Club has ever been preëminent among the advocates of mountaineering. Among its members are many individuals who have contributed to the shaping of National Park Service policies. This club, which was organized about the same time that Yosemite National Park was created, defined its purposes: “To explore, enjoy, and render accessible the mountain regions of the Pacific Coast; to publish authentic information concerning them; to enlist the support and coöperation of the people and the Government in preserving the forests and other natural features of the Sierra Nevada.” For nearly half a century the Sierra Club has centered its attention upon the security and well-being of the natural attributes of Yosemite and has worked to make those attributes known and appreciated. The national parks, national forests, and state parks, generally, have benefited greatly by the continuous interest of the club, and the trail and road systems of Yosemite National Park, especially, have received its study. A New Emphasis on the High Country With the completion of an all-year highway into Yosemite Valley and the realignment of portions of the Big Oak Flat and Tioga roads, the accessibility of Yosemite National Park to the motorist reached its peak, and since that time serious thought has been given to modification of the road system. The Commonwealth Club, in a comprehensive report entitled, “Should We Stop Building New Roads into California’s High Mountains?” concluded that accessibility had already reached, if it had not passed, a desirable maximum, on the basis of a stand for the preservation of mountain wilderness values made by many Sportsmen’s organizations and the Sierra Club. The National Park Service gave consideration, in its Yosemite Master Plan, to the abandonment and obliteration of certain roads which were either superseded by highways or which could be relocated to reduce any detrimental effects upon the mountain landscape. Col. C. G. Thomson led in establishing this trend. Studies were made by the park administration, the concessionaire, and various organizations outside of the park of means by which present-day visitors, who were now arriving by automobile in hurried throngs numbering as many as 30,000 persons on a single holiday week end, might enjoy the park to some degree at least in the manner that the pioneers had enjoyed it. Improvement of the trails, of outlying facilities, education in the means of trail travel, and the development of an all-season program that would help to spread the peak of travel into a plateau, were steps taken and which are being taken in the attempt to halt the tendency of the public to make of Yosemite Valley an urban “resort.”