Yosemite became a national park in 1890. Houses cannot be built in national parks, because they are protected by the federal government. Photographs such as Tutucanula - El Capitan 3600 ft. Yo Semite revealed the beauty of Yosemite to people and convinced them to protect its trees from being torn down for homes and businesses. 

John Conness of California, who served in the U.S. Senate from 1863 to 1869, owned a set of photographs by Carleton Watkins and proposed that Yosemite Valley should be protected from development. In 1864, President Abraham Lincoln signed the Yosemite Valley Grant Act, marking the first time that the federal government reserved land for conservation reasons. Under this act, the state of California was required to protect the Yosemite Valley and the Mariposa Grove (a grove of sequoias in the southern part of what is now Yosemite National Park). The bill decreed that the "premises shall be held for public use, resort, and recreation."