``They're very happy with the black area they have between the active part of the fire and Apgar Village,'' fire information officer Christine Ayers said Tuesday.
Most of the backfire was completed Monday and fire officials were hoping to complete it Tuesday with a smaller fire if weather conditions were ideal.
The fire prompted a new round of evacuations in the park Sunday. Lake McDonald Lodge and two other lodges, along with about a dozen homes and some campgrounds were evacuated.
The fire had grown to about 38,600 acres by Tuesday morning.
Glacier National Park officials said it was not clear when the closed areas would reopen.
The evacuation area is about 10 miles north of West Glacier, the park's gateway town that had been threatened by the fire for more than a week in late July and early August.
Firefighters also would concentrate Tuesday on protecting 13 private homes on the north end of Lake McDonald, Ayers said.
Elsewhere in Montana, a wildfire that began with a lightning strike Friday near Big Timber, about 70 miles west of Billings, had tripled in size to about 34,000 acres and forced the evacuation of some 50 homes. Firefighters were expecting a difficult day Tuesday, with lightning and 45 mph wind gusts.
The blaze was threatening another 70 homes, after burning six outbuildings. More evacuations took place Monday night, said fire information officer Pat McKelvey.
He said the fire crews faced extreme fire behavior Monday and were dealing with a forest as dry as it's ever been. The fire has ``extreme growth potential,'' McKelvey said.
Another fire about 20 miles east of Eureka was estimated at 27,525 acres Monday. And a new wildfire in the Swan Valley grew to 4,000 acres by late Monday, forcing residents in 17 area homes to be ready to evacuate.
After burning for 45 days, fire bosses expressed optimism that Washington state's largest wildfire could be fully contained by late Tuesday.
The blaze has charred more than 81,000 acres, mostly in north-central Washington's Pasayten Wilderness. It was started by lightning June 29.