Firefighters battled Wednesday to save the Alaska oil pipeline from a half-mile-wide inferno, while crews held their ground against the worst of a dozen wildfires that have ravaged 118,000 acres of Yellowstone National Park.

In Alaska, where 51 wildfires were burning over more than 1,669,877 acres, a lightning-sparked blaze rampaged to within 4 miles of the oil pipeline before the Bureau of Land Management spotted it Tuesday, officials said.The BLM declared it a "priority fire" and sent 200 firefighters to protect the pipeline. BLM dispatcher Blair Young said surprising gusts of wind fanned the flames over 5,000 acres of wilderness 7 miles long and a half-mile wide.

"It's hard to say what will happen with this one," Young said. "We should be getting rain at about this time of year. The winds that helped it take off are not typical."

Another new Alaskan fire blackened an estimated 6,400 acres west of Fort Yukon above the Arctic Circle. Fire officials were concerned because residents of the town of 600 were nearly surrounded by heavy smoke from the blaze and two more fires to the north and south.

Elsewhere in the nation's largest state, two huge fires burned on the 8.6 million-acre Yukon Flats National Wildlife refuge. One devoured 486,000 acres north of Fairbanks, destroying several trappers' cabins. Another burned 193,500 acres south of the small community of Birch Creek.

In Yellowstone National Park, most wildfires were controlled or contained, and breezes pushed the 17,700-acre North Fork fire away from the famed Old Faithful geyser. Full containment of the North Fork fire was expected by Friday.

Two fires in Idaho's Boise National Forest were in the mop-up stages Tuesday evening. The 5,010-acre Willis Gulch fire destroyed about $7.5 million in timber and fish and wildlife habitat. By Thursday night, fire officials expect to fully control that blaze and a second fire that destroyed 200 acres of commercial timber.

But gusting winds whipped the Spring Canyon fire in eastern Idaho's Targhee National Forest from 150 acres to 1,280 acres late Monday and early Tuesday. The blaze slowed Tuesday afternoon as winds diminished.

Another blaze broke out Tuesday on rangeland north of Boise, growing to 1,300 acres and burning dangerously close to a home in the Boise foothills. By late evening, however, fire crews reported no threat to the home.

In Montana, the 3,200-acre Rock Creek fire in the Bitterroot National Forest was nearly contained.

Oregon firefighters controlled a 145-acre fire in the Mount Hood National Forest Tuesday evening, but then were called to battle a new blaze that raced across more than 500 acres of rugged Weyerhaeuser Company timberland in Coos County.

Fire officials said flames from the new blaze, dubbed the Burnt Mountain fire, were spotted about noon and spread quickly, leaping a mile ahead of the main fire line and quickly becoming Oregon's largest forest fire on state-protected land so far this hot, dry summer.

In Washington, firefighters mopped up a 3,600-acre forest fire on both sides of the Cascade crest while flames from a wind-whipped fire in the Cascades spread quickly through 120 acres of felled timber.