1690 William Penn requires settlers to preserve one acre of trees for every five acres cleared
1739 Benjamin Franklin petitions Pennsylvania Assembly to stop industries from dumping waste
1827 First volume of Audubon’s Birds of America is published
1845 Thoreau builds his cabin at Walden Pond
1849 Department of the Interior is created
1854 Thoreau’s Walden is published
1868 John Muir first sees the Yosemite Valley
1890 Yosemite National Park is created
1891 The Forest Reserve Act is passed
1892 The Sierra Club is founded
1898 Gifford Pinchot is named head of the Division of Forestry
1905 The National Audubon Society is founded Cordelia Stanwood begins her systematic observations of nesting birds
1910 Cordelia Stanwood begins publishing her nesting bird studies
1934 Roger Tory Peterson creates his bird identification system
1935 TheWildnernessSocietyisformed
1947 Marjory Stoneman Douglas’s River of Grass is published Everglades National Park is created
1949 Aldo Leopold’s Sand County Almanac is published
1960 Arctic National Wildlife Reserve is created, due to efforts by Mardie and Olaus Murie
1962 Rachel Carson’s Silent Spring is published
1964 The Wilderness Act is passed
1970 The Clean Air Act is passed
The first Earth Day is observed
The Environmental Protection Agency is created
1989 The Exxon Valdez oil spill occurs in Alaska
2006 Al Gore’s An Inconvenient Truth is published
2011 The BP oil spill occurs in the Gulf of Mexico