Final answer:
Americans established formally protected areas after the Civil War to preserve and protect the natural resources and beauty of the land.
Step-by-step explanation:
Americans established formally protected areas after the Civil War to preserve and protect the natural resources and beauty of the land. The westward expansion and industrialization that followed the war led to the exploitation of natural resources such as mining, logging, and agriculture. To prevent further damage to the environment and to create areas for public enjoyment, the federal government established national parks and protected lands. The Yosemite Grant Act, signed by President Lincoln in 1864, set a precedent for the preservation of natural lands, and the Yellowstone National Park Protection Act, signed by President Grant in 1872, created the first national park in the United States.