WASHINGTON (AFP, REUTERS) - An American woman has been found alive six days after her car flew off a highway and landed on a mesquite tree in the state of Arizona, police said on Wednesday (Oct 31).

The 53-year-old woman was travelling on national route 60 near Wickenburg, about 80km north of Phoenix, when she lost control on Oct 12, the Arizona Department of Public Safety said in a news statement.

She crashed through a highway railing and plunged 17m into the tree where the vehicle "remained suspended above the ground", the state troopers said.

"There were no apparent witnesses to the crash and it would be six days before the woman would be discovered by the authorities," the troopers said.

On Oct 18, rancher Dave Moralez, 30, and a road maintenance crew were working to corral a cow on US Highway 60 when they noticed a break in the fence near the road.

They saw the mangled car below, and when they climbed down, found footprints leading from the vehicle.

They followed the tracks and discovered the severely dehydrated woman, her eyes swollen, wearing a T-shirt, shorts and flip-flops, suffering from broken ribs, a dislocated shoulder and a head injury, Moralez told a local NBC affiliate.

"I don't know if she could have made it there another night," Moralez said.

DPS director Frank Milstead praised the highway workers and the rancher.

"Due to their outstanding efforts, this woman's life was saved," he said in a statement.

The woman told the trooper that she stayed inside her vehicle for "several days" before she climbed out and tried to walk towards railroad tracks in the hope she would be found.

But she was too weak to make it.

The woman was taken by helicopter to hospital after her rescue.