 Overgrazing of meadows ( especially by sheep ) , logging of giant sequoia , and other damage caused Muir to become an advocate for further protection . Muir convinced prominent guests of the importance of putting the area under federal protection ; one such guest was Robert Underwood Johnson , editor of Century Magazine . Muir and Johnson lobbied Congress for the Act that created Yosemite National Park on October 1 , 1890 . The State of California , however , retained control of Yosemite Valley and Mariposa Grove . Muir also helped persuade local officials to virtually eliminate grazing from the Yosemite high country . 
