As the American frontier surrenders to human settlement, philosophers, writers, conservationists, and politicians work to interpret the value of natural resources in a country of seemingly endless bounty.
"To a person sitting quietly at home, Rocky Mountain traveling, like Rocky Mountain scenery, must seem very monotonous; but not so to me, to whom the pure, dry mountain air is the elixir of life. "
A Lady's Life in the Rocky Mountains, 1879
1854 - Transcendentalist Henry David Thoreau, author of Walden, writes that wilderness sanctuaries are the "need of civilized man."
1856 - Artist Thomas A. Ayers' lithographs introduce Yosemite to the East. Country Gentleman republishes articles that declare the Yosemite Valley to be "the most striking natural wonder on the Pacific."
1861 - Photographs by Carleton E. Watkins make Yosemite Valley famous.
1864 - Frederick Law Olmstead pushes for protection of Yosemite Valley and is first to advance the idea of placing certain areas under government protection.
1864 - A major turning point in the conservation movement occurs when George P. Marsh publishes Man and Nature, warning citizens to stop the devastation of natural resources.
1864 - President Abraham Lincoln signs the Yosemite Bill "to protect an area and conserve it for recreational enjoyment."
1865 - Walt Whitman writes "Give Me the Splendid Silent Sun," which reflects contradicting public views of conquering nature and respecting it.
1867 - The Alaska Purchase is signed by President Andrew Johnson, adding 365 million acres of public lands to the United States.
1867 - Kiowa Chief Satanta voices opposition to construction of the Union Pacific Railroad at a council held at Fort Larned, Kansas.
1869 - Transcontinental travel becomes available to the public when the Union and Pacific Railroads meet at Promontory Point, Utah.
1869 - John Wesley Powell begins a three-month river trip down the Green and Colorado Rivers, including the first passage through the Grand Canyon. His diary and later publications generate public interest in the Grand Canyon.
1871 - Yellowstone is documented by the official U.S. expedition of geologist Ferdinand Hayden, painters Henry Elliott and Thomas Moran, and photographer William Henry Jackson.
1872 - Artist Thomas Moran exhibits paintings of Yellowstone, helping to promote establishment of the first national park. Yellowstone is designated a "public park or pleasuring ground for the benefit and enjoyment of the American people."
1874 - Surveyors, escorted by the 7th U.S. Cavalry under the command of Lieutenant George A. Custer, penetrate the Black Hills of South Dakota, an area considered sacred by the Sioux tribes.
1876 - Battle of the Little Bighorn occurs in Montana on what is now the Little Bighorn Battlefield National Monument.
1877 - After fleeing, Chief Joseph of the Nez Perce surrenders to Generals Howard and Miles 30 miles from the Canada border stating, "I will fight no more forever."
1890 - The needless slaughter of 150 Sioux at Wounded Knee in South Dakota results in the surrender of Indians, bringing the wars between whites and Indians to an end.
1890 - The Yosemite Reserves Act is passed by Congress and signed into law by President Benjamin Harrison, creating Yosemite National Park.
1892 - Conservationist John Muir organizes the Sierra Club to enlist public and governmental support for preservation of wilderness.
1892 - Casa Grande Ruins N.M. becomes the first prehistoric cultural site to be protected by the federal government.
1893 - Professor Frederick Jackson Turner reads his paper, "The Significance of the Frontier in American History," at the American Historical Association meeting in Chicago, stating that the frontier is closed.
1898 - Gifford Pinchot takes office as Chief of the Division of Forestry, later organized into the National Forest Service in 1905, advancing conservation of natural resources.