Wilds Act now 40 years old

The 1964 Wilderness Act was passed overwhelmingly by both houses of Congress and signed into law by President Lyndon B. Johnson. The law defined wilderness as land that retained its "primeval character and influence, without permanent improvements or human habitation."

The law initially set aside 9 million acres and declared that those lands and later acquisitions should be administered in a manner that would "leave them unimpaired for future use and enjoyment as wilderness."

Road building, oil and gas drilling, logging and off-road vehicles were banned, along with new mining claims, new reservoirs, power lines and pipelines. Congress allowed some long-standing mining operations and livestock grazing to continue.

Over the past 40 years, the national wilderness system has grown to 105 million acres. More than half of it is in Alaska. Much of the rest is scattered through some of the nation's most dramatic mountain country: California's Sierra Nevada; Washington's North Cascades; and along the spine of the Rockies in Montana, Idaho, Wyoming and Colorado.

Until now, every president since Johnson, except Richard Nixon, has added at least 3 million acres to the nation's store of wilderness.