The main western highway into Yosemite National Park is reopening after firefighters pushed back flames that have charred about 50 square miles just outside the park.

Authorities had temporarily shut down a 10-mile stretch of Highway 140 to keep flames from leaping across the Merced River canyon earlier this week. The road reopened Wednesday morning, but officials are still recommending tourists take alternate routes into Yosemite to give fire engines enough room to maneuver.

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The blaze raging since Friday has destroyed 21 homes and is only 20 percent contained.

Fire officials previously said 25 homes burned down, but revised their assessment Wednesday after discovering four of the structures were outbuildings.

Meanwhile, the wildfires have hurt the area's tourism industry, which had just begun to thrive again.

Vendors along one of the main roads leading to Yosemite National Park this summer were finally seeing business turn around following a rock slide that kept tour buses away for the previous two years.

But that was before the massive wildfire closed the highway and sent towering plumes of smoke and ash over one of the nation's most celebrated wilderness areas.

"It's like we just get on our feet and they kick the stool out from under us," said Donna Santi, a gift shop clerk in Mariposa. "Still, the business will survive. We're more worried about the residents."

Tuesday, visitors seeking to photograph Yosemite National Park's famed peaks instead took shots of monoliths obscured by flying ash blowing in from an out-of-control wildfire burning just 12 miles outside the park.

The haze has left one of California's most popular destinations shrouded in smoke at the height of Yosemite's busiest season.

"It's the views that are really disappointing," said Karen Brown, a 45-year-old mother of two from Phoenix, Ariz. "We do two major trips a year and this was one of them. It's not like we can shoot back here in a month."

Brown said her family was packing up a day early to avoid suffering from irritated eyes and sore throats. The children had been "using their imaginations to experience Yosemite," she said, but ventured they would prefer clear views of Lake Tahoe.

Visitors seeking to enter the park from the west were turned around Tuesday, when authorities temporarily shut down a 10-mile stretch of Highway 140 to keep flames from leaping across the Merced River canyon. The road reopened Wednesday, but officials were still recommending tourists take alternate routes into the park to give fire vehicles enough room to maneuver.

The western gate itself remained open, as did other entrances to the park, and many travelers said they were gladly staying put.

Patricio Aguirre, 48, from the province of Buenos Aires, Argentina, smiled as his wife and children marveled, through a white haze, at Half Dome's imposing shoulder.

"It's a great shame because we know what's burning now won't regenerate for many years," Aguirre said, as he climbed into the family's rented minivan. "My children laugh at me, but I tell them they have to see the good in this. It's not every day one can see Yosemite burn."

Authorities said the blaze roaring through a dry river canyon 18 miles from the valley floor had charred more than 50 square miles of steep, rugged terrain since a target shooter sparked the wildfire on Friday.

It has also forced the evacuation of 350 homes in the towns of Midpines and Coulterville, gateway communities whose businesses rely on tourist dollars to stay afloat.

Fire crews expected to get some help from a slight drop in temperatures, which were forecast to remain in the high 80s Wednesday, accompanied by low humidity and light winds, the National Weather Service said.

At summer's peak, as many as 4,000 visitors a day stream into the park, and rangers expect the fire will keep very few people away.

Officials with DNC Parks and Resorts at Yosemite, which manages restaurants and lodging in the park, said only about 2 percent of all overnight guests have asked for refunds since Saturday, when the transmission line that fed power to Yosemite was destroyed in the fire.

Hotels, stores and most restaurants in the park have remained open, but have been operating on generators. Tuesday, 245 guest rooms at the Yosemite Lodge at the Falls remained without power, and lodge staff were handing out flashlights and offering free hot showers at nearby Curry Village. Limited electricity was restored Tuesday afternoon in the outlying community of El Portal, near the park's western boundary.

"We're seeing a few people departing maybe because they have health concerns about the air quality, but virtually everyone's staying in the park," said Kenny Karst, a spokesman for the concessionaire. "Our main message is we're open. The stables are open, we've got river rafting, and we're leading all kinds of hikes and trips to the backcountry."

In all, more than 2,000 blazes have scorched about 1,700 square miles around California — mostly on national forest land — this year.

Meanwhile, Gov. Arnold Schwarzenegger on Tuesday announced a $50,000 reward for information leading to the person who ignited a destructive wildfire last month.

The mid-June blaze destroyed 87 homes in and around the town of Paradise and charred more than 23,000 acres in Butte County, about 90 miles north of Sacramento. The Sierra foothills town east of Chico is home to about 30,000 residents, including many retirees.

The fire contributed to at least one death, an elderly woman who suffered a heart attack while evacuating.

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