Flames from a huge wildfire burning through a national forest inched toward the scenic tourist town of Big Sur, where firefighters rushed Thursday to protect historic structures and hundreds of homes.

As the lightning-sparked blaze crept closer to California's coastal Highway 1, fire engines stood guard next to rustic buildings as thick smoke and ash drifted over the Pacific Ocean while more than 1,000 wildfires blazed across the northern half of the state.

Firefighters fortified their lines near populated areas but were letting the fire rage nearly unchecked through steep mountain forests as flames torched massive redwoods and sent them toppling.

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The blaze in the Los Padres National Forest was only 3 percent contained and had burned nearly 42 square miles near the coast about a mile south of Big Sur, officials said. It has destroyed 16 homes since breaking out Saturday.

Authorities asked residents to evacuate 75 homes along a ridge threatened by the blaze. About 575 homes were threatened in all.

A spokeswoman for the California Department of Forestry and Fire Protection (CALFIRE) said cooler weather had allowed firecrews to make inroads but the prospect of more thunderstorms was a concern.

"If the storms come without rain and more lightning it could be a concern," Cheri Patterson told AFP.

"The biggest difficulty we have had so far is the number of the fires. At this stage we have more than 1,000. It has stretched our resources."

"This is not going away anytime soon," said Mark Savage, a spokesman for the U.S. Forest Service. "We're gearing up as opposed to gearing down."

Authorities closed a long stretch of the Pacific Coast Highway threatened by the blaze, shutting off access to several lodges, restaurants and art galleries that depend on tourist traffic. Motorists who had planned to drive south along the coast were forced to turn around.

Dutch travelers Joost Ueberbach, 28, and Gemma Arts, 27, wanted to drive through Big Sur on their way to Los Angeles from San Francisco but ran into the roadblock Thursday.

"We knew there was a fire somewhere, but we didn't know the road was blocked," Ueberbach said. "We had hoped to see the nice views of the coastline. I guess it's just bad luck."

A popular tourist spot along the towering coastal cliffs, Big Sur is also a storied destination for generations of American writers and artists.

Fire crews on Thursday beat back flames that threatened a small roadside library named after "Tropic of Cancer" author Henry Miller, who lived in Big Sur for years.

Down the road, crews maintained fire lines and doused flames near the wooden cabins of Deetjen's Big Sur Inn, which had been evacuated Sunday morning.

Hal Newell, who lives in a small wooden house on a ridge just above the bed and breakfast, dropped by to check on his home for the first time since he and his family fled five days earlier.

"I feel real glad to still have a place to live," said Newell, who has lived in Big Sur since he was born in 1938.

The National Weather Service predicted more dry lightning toward the end of the week, although forecasters did not expect as severe an electrical storm as occurred last weekend, when nearly 8,000 lightning strikes sparked about 800 fires across Northern California.

The state's largest fire, about 20 miles east of Big Sur in a more remote area of the Los Padres forest, also continued to vex firefighters, having scorched more than 92 square miles and destroyed two homes. The blaze, sparked by a campfire on June 8, was 71 percent contained.

Monterey County sheriff's officials said mandatory evacuation orders were in place for both fires, but they could not specify how many people were forced from their homes.

Gov. Arnold Schwarzenegger visited to assess the damage and said he has called in the National Guard to help fight the fires.

The governor also visited Butte County, where 29 fires covering about 11 square miles raged were threatening 1,200 homes. The blazes, which were only 5 percent contained, cropped up just as the county was recovering from a fire that charred 74 homes and 36 square miles earlier this month.

Areas hit the hardest by the lightning storm also included Mendocino County, where 106 fires have burned more than 33 square miles and destroyed two homes and the Shasta-Trinity Forest, where more than 150 fires have burned about 34 square miles and forced several evacuations.

Altogether, the region's wildfires had burned almost 250 square miles despite the efforts of more than 12,000 firefighters and crews from 41 states.

In rural Lake County, a fire that had burned more than 20 square miles since Sunday sent smoke drifting 150 miles south to the San Francisco Bay Area, where air quality warnings were in effect.

Smoky air also forced the cancellation the 100-mile Western States Endurance Run for the first time in the race's 31-year history.

The threat of fire has already led communities across Northern California to nix plans for Fourth of July fireworks.

In central New Mexico, Torrance County sheriff's deputies went door to door Thursday urging people to leave about 50 homes northeast of a forest fire in the Manzano Mountains that earlier led to the voluntary evacuations of about 350 people.

Those who had already left are from Tajique and two subdivisions on the eastern side of the mountains, said Vicki Fox, a fire information officer.

The blaze, started by lightning Monday night, had charred 5 1/2 square miles of thick stands of mixed conifers, ponderosa pine, pinon and juniper by Thursday night.

A nearly 4-square mile fire in Arizona in a dry riverbed cast a pall of smoke visible across much of the Phoenix area. The fire, believed to have been started by lightning Wednesday afternoon, was not threatening any homes, but several residents voluntarily left that night, said Dave Martin, Gila River deputy fire chief.