The Democratic-led U.S. Congress gave final approval on Wednesday to sweeping land and water conservation legislation that environmental groups praised as one of the most significant in U.S. history.

The measure, a package of more than 160 bills, would set aside about 2 million acres -- parks, rivers, streams, desert, forest and trails -- in nine states as new wilderness and render them off limits to oil and gas drilling and other development.

The House of Representatives approved the measure on a vote of 285-140 a week after it cleared the Senate, capping years of wrangling and procedural roadblocks.

It now goes to President Barack Obama to sign into law, which he is expected to do swiftly.

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 deny access for oil and gas drilling and said House Democrats refused to consider changes.

The 2 million acres that would be designated as new wilderness are mostly in California, followed by Idaho, Utah, Colorado, Oregon, Virginia, West Virginia, New Mexico and Michigan.

Separately, the legislation would permanently protect and restore a 26 million-acre (10.5 million-hectare) system composed of the U.S. Bureau of Land Management's most historic and scenic lands and waters, including the Canyons of the Ancients in Colorado and Red Rock Canyon outside of Las Vegas.

Environmental and historic groups praised the legislation.

Future generations will look back at this day as a major milestone in our nation's conservation history, said William Meadows, president of the Wilderness Society.

It has been a long and difficult road, but today, Congress acted on behalf of hunters and anglers who understand the need for intact habitat, said Tom Reed of Trout Unlimited.