Efforts to protect Yosemite Valley began as far back as June 30, 1864 when President Abraham Lincoln signed a bill granting Yosemite Valley and the Mariposa Grove of Giant Sequoias to the State of California as an inalienable public trust. This was the first time in history that a federal government had set aside scenic lands simply to protect them and to allow for their enjoyment by all people. The area became a national park on October 1, 1890 following several years of struggle by John Muir against the devastation of the subalpine meadows surrounding Yosemite Valley.Despite its national park status, California controlled the initial grant area until 1906. Prior to ceding control, the city of San Francisco became embroiled in a bitter political struggle over the Hetch Hetchy Valley, in which the city wanted to dam the Tuolumne River as a source of drinking water and hydroelectric power. In 1913, conservationists led by John Muir lost the battle when Congress passed the Raker Act, authorizing the construction of O'Shaughnessy Dam. To this day crusades to restore Hetch Hetchy are ongoing.Yosemite has grown from a little visited, yet historically significant, park to one of the "crown jewels" of the US National Park System. With this stature comes difficulties; current visitation numbers roughly 3.5 million visitors per year, with a majority visiting 12 square miles within Yosemite Valley (about 1% of the total park land). The dual role of the park service -- protection of the resource and provide for the enjoyment of the visitor -- makes sure that Yosemite continues to be an important breeding ground for management ideas about US National Parks. http://wikitravel.org/en/Yosemite National Park