The birthdates of its trees are lost to history , so Muir Woods did the next best thing Wednesday and celebrated its 100 - year anniversary as a national monument . Just for good measure , it got itself listed in the National Register of Historic Places . Politicians , rangers , John Muir look - alikes and conservationists made speeches , planted rhododendrons , ate cake and waxed poetic about the big trees Wednesday , the biggest event in a yearlong celebration of the establishment of the Muir Woods National Monument . " I think we ' re standing right now in heaven on earth , " declared Rep . Lynn Woolsey , D - Petaluma , as she stood before a crowd of several hundred people shivering in the cold morning mist amid the giant redwoods . Muir Woods ' listing in the National Register , which is administered by the National Park Service , was timed to coincide with the anniversary of the day President Theodore Roosevelt declared it the nation ' s 10 th national monument . The famous redwood grove was listed , according to park historian Stephen Haller , not only because of the ancient trees but because of its importance as the birthplace of the modern conservation movement . " It ' s a historic site because it changed people ' s lives , their thinking and the politics of land use , " Haller said . Muir Woods would almost surely have been logged and flooded with a dam had U . S . Rep . William Kent not purchased the land and donated it to the federal government . By then the vast old - growth redwood forests that once covered much of the California coast had been chopped down and used to build San Francisco and other cities . The forests , which covered 2 million acres in the early 19 th century , were reduced by more than 97 percent . The giant sequoias in what was then known as Redwood Canyon still existed in the early 20 th century only because of their remote location . But pressure from logging interests was mounting , and the wildlife was disappearing . The last grizzly bear in Marin County was killed in the canyon in 1903 . Kent , the heir to a Chicago meat - packing fortune , organized the Tamalpais Forestry Association and in 1905 bought the canyon for $ 45 , 000 from the Tamalpais Land & Water Co . That might have been enough to save the land had the 1906 earthquake and fire not created a need for both lumber and a reliable water source for the region . The North Coast Water Co . proposed damming Redwood Creek and filed condemnation papers in an effort to take Kent ' s land . But Kent and his wife , Elizabeth Thacher Kent , thwarted the land grab , donating 298 acres of forest to the federal government on Dec . 26 , 1907 . Kent ' s wife was initially leery of giving away such a valuable asset , but her husband reportedly responded , " If we lost all the money we have and saved these trees , it would be worthwhile , wouldn ' t it ? " Roosevelt wanted to name the monument after Kent that day a century ago , but the legislator insisted that it be named after naturalist John Muir . Later additions expanded the monument to 550 acres . Rep . Kent went on to co - author the act that created the National Park Service in 1916 . Kent ' s generous act , which jeopardized his own financial well - being for the good of the people , is now considered one of the most courageous acts of land preservation in U . S . history , inspiring generations of conservationists throughout the region . " It ' s wonderful to see so many people honoring these trees and my grandparents , " said Kent ' s granddaughter , Eleanor Kent , who was at the centennial with several other Kent descendants . " I hope to carry on the tradition of creativity and generosity that he and his wife established . " At the ceremony , actor and storyteller Garth Gilchrist dressed up as John Muir and in an authentic Scottish brogue addressed the crowd , reincarnating words spoken by Muir in 1897 about the vanishing redwoods that still resonate today . " God has cared for these trees , saved them from drought , disease , avalanches and a thousand straining , leveling tempests and floods , " Muir said , " but he cannot save them from fools - only Uncle Sam can do that . " Muir Woods joins dozens of other Bay Area sites , including Alcatraz , Aquatic Park , the Farallon Islands , Angel Island , China Camp State Park and Rancho Olompali , on the list of national historic sites .