The crowning achievement of the returning expeditions was helping to save Yellowstone from private development. Langford and several of his companions promoted a bill in Washington in late 1871 and early 1872 that drew upon the precedent of the Yosemite Act of 1864, which reserved Yosemite Valley from settlement and entrusted it to the care of the state of California. US National Parks History
The United States has 63 National Parks but here is a list of the ten oldest parks. Ten Oldest US National Parks
Which is the oldest National Park? Did other national parks exist before Yellowstone? Yellowstone or Yosemite?