While writers such as John Muir and Bob Marshall had long argued that there was a need to protect wilderness areas, it was not until the passage of the Wilderness Act in 1964 that federal policy makers took a significant step beyond the “wise use” philosophy of the Progressive era. In 1956 the executive director of the Wilderness Society, Howard Zahniser, proposed legislation that would permanently protect millions of acres wilderness areas located in the national parks and forestreserves. Senator HubertH. Humphrey (D-MN) and Representative John Saylor (R-PA)introduced such a bill the following year. After numerous revisions, the bill was signed into law by President Lyndon B. Johnson on September 3,1964. While the law’s final definition of wilderness was more limited than many wilderness advocates had hoped, and the bill itself left the thorny issue of designating future wilderness areas largely unresolved, it was still a legislative milestone in wilderness protection and codified the desirability of creating a National Wilderness Preservation System.