Briefly describe each of these aspects of u. s. environmental history: protection of forests, establishment and protection of national parks and monuments, conservation in the mid-20th century, and the envi - ronmental movement of the late twentieth century.

The practice of forest conservation began with the efforts of former president of the United States Theodore Roosevelt and the first president of the United States Forest Service Gifford Pinchot, who wanted to asses the condition and quality of the national forests and oversaw the conservation and reclamation of forest land. It was in 1916 that the National Park Service was created following the Organic Act which states that the purpose of protecting national parks, monuments and reservations is "to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations."

The conservation of forest land in the country continued in the mid-20th century with president Lyndon B. Johnson who signed The Wilderness Act which aims to protect the total amount of federal land recognized as wilderness, described as "an area where the earth and community of life are untrammeled by man, where man himself is a visitor who does not remain" and lead to the creation of the National Wilderness Preservation System.

The environmental movement for preservation of natural resources and public health began throughout the 60's and 70's, when oil spills, the heavy use of insecticides, air pollution and natural disasters became the widespread concern of the american public. This movement evolved towards the end of the century when its focus changed primarly to climate change and the consequences of industries abusing wilderness land and natural resources for their own benefits.