Pine Valley, Calif. ? Motorists have become afraid to drive at night along a stretch of freeway outside San Diego, scared that a vehicle going the wrong way will come hurtling out of the darkness.

The wrong-way drivers are immigrant-smugglers trying to skirt a Border Patrol checkpoint in the pine-covered mountains east of the city.

The 30-mile stretch of Interstate 8, the main route between San Diego and the desert along the Mexican border, has been the site of deadly crashes and hair-raising close encounters for years.

But commuters and California Highway Patrol officers say that the wrong-way drivers have become an almost nightly phenomenon since the summer.

Smugglers seem to know that Border Patrol and CHP vehicles will not chase them as they speed westbound in the two eastbound lanes of I-8.

“I think they learned they get away with it,” CHP Sgt. Leslie Lazo said. “It’s just a recipe for disaster.”

Immigrants usually cross the Mexican border on foot in the rough desert, then cram into a van or pickup truck headed north.

As they approach the flashing lights of the westbound I-8 checkpoint, where two Border Patrol officers peer into vehicles and search any deemed suspicious, smugglers steer up a 20-yard slope into the eastbound lanes, often at night with their headlights turned off.

Mary Schoepper, a 67-year-old real estate broker who lives about three miles from the border, has been behind the wheel in two near-collisions with wrong-way drivers since spring — one at night and one in the middle of the afternoon. Now, she checks into motels rather than drive home after late nights at work.

“When I first moved out here, you used to look out for deer crossings,” said Schoepper, who has lived in the hamlet of Boulevard since 1988. “Now you look out for deer crossings and Mexicans driving the wrong way on the freeway.”

On Aug. 31, a Chevrolet Astro Van drove against oncoming traffic for about 17 miles before swerving back into the westbound lanes. The van, reaching speeds of about 100 mph, spun out of control and crashed, injuring 19 suspected illegal immigrants. The driver escaped.

In June 2002, a van carrying 27 people collided with a Ford Explorer: Five people in the van, including the driver, were killed, along with a man in the sport utility vehicle.

The wrong-way driving is said to reflect growing desperation among smugglers since federal authorities in 1994 made it harder to cross the border between Tijuana and San Diego. The stepped-up patrols near metropolitan San Diego have led immigrants to try to cross the border farther to the east.

Neither the Border Patrol nor the CHP keeps statistics on wrong-way drivers, but the outbreak appears concentrated in rural San Diego County. Authorities in Arizona and in El Paso, Texas, said they have not seen similar increases.