Four robotic vehicles have finished a Pentagon-sponsored race across Nevada's Mojave desert, leading scientists to hail a technological milestone.
"The impossible has been achieved," said Stanford University's Sebastian Thrun after its customised Volkswagen, Stanley, crossed first on Saturday.
Twenty-three self-driving racers took part in the Grand Challenge race which offered a $2m (£1.1m) prize.
Vehicles had to negotiate 240km of rocky terrain. Last year none finished.
The challenging competition was run by the US Defense Advanced Research Projects Agency (Darpa).
The vehicles, guided by sophisticated software, gave scientists hope that robots may one day take part in battles without endangering soldiers.
The driverless vehicles ranged from souped-up SUVs (sports utility vehicles) to hi-tech dune buggies.
Also finishing was a converted red Hummer called H1ghlander and a Humvee named Sandstorm from Carnegie Mellon University.
"I'm on top of the world," said Carnegie Mellon's robotics professor William 'Red' Whittaker, adding that a mechanical glitch allowed Stanley to pass H1ghlander.
The race favourite, a Ford Escape Hybrid by students in Metarie, Louisiana, came in fourth.
The race was organised by the Pentagon's defence agency to push research into autonomous vehicles for the US military. This year it doubled the prize fund for the challenge.
Driverless vehicles that can withstand such punishing conditions could be used to carry crucial supplies for the military in war zones.
The vehicles were kitted out and modified with GPS (global positioning satellite), cameras, infrared sensors, computing equipment, and lasers to guide them across the tough terrain.
They were not allowed to be controlled, even remotely, by humans.
"We can now see a future where these vehicles will take the place of soldiers in harm's way," said Ron Kurjanowicz, manager of the Darpa Grand Challenge race.
Stanford University students hoisted their team captain Mr Thrun on top of their shoulders after their win.
Earlier, Mr Thrun said he was confident this year's race would produce a winner and about the future for autonomous vehicles.
"It's a no-brainer that 50 to 60 years from now, cars will drive themselves," he said.
The 23 finalists were chosen after eight days of qualifying events over much shorter courses.
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Forty-three teams battled it out to take a place in the final, including teams from inventors, universities and a high school.
They were among 195 teams that originally applied to take part in the gruelling cross-country challenge.
The 23 final entrants had 10 hours to complete the race, which included a human-made obstacle course.
But the precise route was kept secret until two hours before the competition.
The teams had varying levels of sponsorship to develop their desert robots.
Some had millions pumped into the projects from corporate sponsorship, while others scraped together much less funding.