The US Congress has voted to set aside more than 2 million acres in nine states as protected wilderness – from California's Sierra Nevada mountains to the Jefferson National Forest in Virginia.
Environmentalists hailed the legislation, which will block oil and gas development on vast swaths of federal land, as the most significant in US history. President Barack Obama is expected to quickly sign it into law.
The bill unites almost 170 separate measures and represents one of the largest expansions of wilderness protection in decades. It grants the government's highest level of protection to land across California, Colorado, Idaho, Michigan, New Mexico, Oregon, Utah, Virginia and West Virginia.
The bill also protects land in Alaska under a controversial land swap that allows the state to build a planned airport access road in a remote wildlife reserve near the Bering Sea. Critics call the project a "road to nowhere".
Environmental groups and lawmakers in both parties have long pushed for the bill, which will strengthen the national park system, restore forests, preserve rivers, protect historic battlefields and allow more balanced management of public lands.
"I can't think of a single bill that has ever done more to ensure the enjoyment of, and access to, wilderness areas and historic sites," said Democratic Senator Jeff Bingaman who chairs the energy and natural resources committee. Opponents, most of them Republican, complained the legislation would prevent drilling for oil and gas.
The legislation will also permanently protect and restore a 26m-acre mix of the US Bureau of Land Management's most historic and scenic lands and waters, including the Canyons of the Ancients in Colorado and Red Rock Canyon near Las Vegas.
Nick Rahall, chairman of the House Natural Resources Committee, said the bill "represents a new dawn for America's heritage and American values".
Critics said the measure would lock up millions of acres of land that could be explored for energy and used for other development.
Doc Hastings, a Republican congressman, said: "Our nation can't afford to shut down the creation of jobs for jobless Americans, and we can't afford to become even more dependent on foreign sources of energy." The bill "even locks up federal lands from renewable energy production, including wind and solar," he said.
Sharon Buccino, of the Natural Resources Defence Council, said the new act did not directly undo any of George Bush's actions, and that it was impossible to know whether it would have passed into law under the previous administration. "You can't say that [Bush] stood in its way because it never reached his desk," she said.
Land to be protected in the bill ranges from California's Sierra Nevada and Oregon's Mount Hood to Rocky Mountain National Park in Colorado and parts of the Jefferson National Forest in Virginia. Land in Idaho's Owyhee canyons, Pictured Rocks National Lakeshore in Michigan and Zion National Park in Utah would also win designation as wilderness, and more than 1,000 miles of rivers in nearly a dozen states will be protected.
The proposals expand wilderness designation — which blocks almost all development — into areas that are currently not protected.
The Alaska provision allows the state to proceed with plans to build an airport access road through the Izembek National Wildlife Refuge as part of a land swap that transfers more than 61,000 acres to the federal government, much of it designated as wilderness.
The project calls for a gravel road through the refuge, which is home to hundreds of thousands of migratory birds, salmon, caribou and other animals. Environmentalists say it would be a disaster. Supporters, including all three Alaska members of Congress, say the road is needed to connect a remote village on the Bering Sea that currently uses a hovercraft to reach an airport and hospital.
The widespread protection for wilderness areas contrasts with efforts under former President Bush to open up unspoilt areas to development. In January last year, the Bush administration announced plans to open more than 3m acres of Alaskan wilderness to logging, mining and road building, angering environmental campaigners who said it would devastate the region. They are urging President Obama to reverse the decision.