MINNEAPOLIS -- Peter Stellpflug loved his Farmall 300.
The vintage tractor didn't go very fast, but Stellpflug liked to use it to putter around his hobby farm in Eyota, Minn. He grew up on a farm outside Rochester using the same type of machine.
Built in the 1950s, the Farmall is known as a "tricycle" tractor because it features two small, close-set wheels made to fit between rows of planted crops. Such tractors are considered dangerously unstable. Typically they lack cabs to protect the farmer if they tip over. But the old machines remain popular.
In October 2011, Stellpflug's tractor rolled while he was mowing grass on a steep hill. He died from his injuries.
"I hated that tractor," said his widow, Tammy Stellpflug. "This is an accident that never should have happened."
Tractor rollovers have been the top cause of death on the family farm for decades, even though engineers long ago figured out how to build a safer machine. Roll bars and enclosed cabs that modern tractors come with greatly reduce the danger.
Other countries insist on such rollover protective structures, as they are known. But the United States allows hundreds of thousands of older tractors to remain in use without the safeguards. It also allows farmers to remove the safety features, and some do.
"We know Europe virtually eliminated rollover deaths because of their insistence on rollover protection," said Matt Keifer, director of the National Farm Medicine Center in Wisconsin. "I don't know why it is taking so long for us to figure this out."
More than 1,700 U.S. farmworkers died in tractor accidents from 2003 to 2013, and the most common thing to go wrong was a rollover. Those accidents accounted for 40 percent of all tractor fatalities -- including at least 30 in Minnesota.
The majority of tractor deaths in Minnesota occurred on machines without rollover protection, records show.
There is no doubt about the effectiveness of roll bars and cabs, which create a protective zone around an operator. According to the National Institute for Occupational Safety and Health, the devices are 99 percent effective in preventing death or serious injury in a tractor overturn when used with a seat belt.
If every tractor in the United States had rollover protection, the institute predicts, nearly 1,000 lives could be saved over the next 10 years.
Scientists, manufacturers and regulators have asked the government to help. But requests for tax breaks, financial incentives or tough new regulations have gone nowhere. Manufacturers began voluntarily putting rollover protection on new tractors in 1985, but 40 percent of the tractors in use on American farms are older and still lack the technology, according to federal estimates.
"The theory was that the old, dangerous tractors would be cycled out of service, and we'd be left with a fleet that's safe," said John May, founder and longtime director of the New York Center for Agricultural Medicine and Health. "But not all of us believe that is going to happen."
Upon requiring rollover protection for new tractors, other countries have typically given farmers five to 10 years to retrofit older machines. But the United States, where farmers are often exempt from regulations that cover other industries, has never taken that step.
Instead, the decision to upgrade is being left to farmers. Many pass, even if they are aware of the safety advantages, either because they can't afford to make the change or because they think their skills offset any dangers, studies in several states show.
So far, only a few states have created programs to help farmers who want the technology, but the efforts are underfunded and barely chipping away at the problem. In Wisconsin, where there are roughly 100,000 tractors without the devices, it took two years to find enough donors to help modify 103 tractors. Like most states, the program receives no public money.
Minnesota doesn't have a program, and farm advocates said they are not pursuing one.
"Our government has become progressively less likely to fund things like this," said Keifer, whose center is sponsoring the program in Wisconsin. "It's just not a priority."
Sometimes even repeat mishaps won't break a farmer's loyalty to a beloved tractor.
Duane Fuglie paid $150 for his 1947-model Allis-Chalmers tractor in 1969. He re-engineered the machine so he can drive backward, with the big wheels in front and the tiny ones in back.
Some farmers believe such modifications make a tractor more dangerous. By 2010, Fuglie's family members had tipped his vintage machine four times. But Fuglie stands by his tractor. He says it can handle a heavy load as well as a modern machine can.
"You can't make it idiot proof," said Fuglie, who was involved in one of the incidents. "You can still screw up if you do the wrong thing."
Just before Thanksgiving 2010, his 24-year-old grandson Jake borrowed the tractor to plow 10 inches of snow from his mother's driveway in Ulen, about a mile from his grandfather's farm.
But Jake got too close to the edge of the driveway and tipped on a gentle slope. "I don't think he did anything wrong," said Jake Schreiner, the only eyewitness.
Jake Fuglie died at the scene.
His mother, Gayle Lund, said she was always afraid that her son, who built grain bins for a living, would get killed while working 80 feet in the air. He would send her photos to prove he was wearing a harness and other safety gear. She said Jake made sure that the 1976-model tractor he bought to farm her property came with a protective cab.
Lund is furious that Duane Fuglie let her son drive a tractor that had tipped over four times.
"If I had known about this, I never would have let that tractor on my farm," Lund said. "It doesn't happen four times by accident. ... I blame the tractor completely. It is obviously unstable."
Duane Fuglie refuses to believe the tractor had anything to do with the crash.
"If I had any inkling there was something wrong with this tractor, I never would have let it go," said Fuglie, who continues to use the Allis-Chalmers tractor for farm chores. "I loved my grandson dearly."
Deputy Scott Steffes, who investigated the accident for the Clay County Sheriff's Office, said the design of the tractor turned a small mistake into a fatal error.
"I don't know if I'd put 100 percent of the blame on the tractor," Steffes said. "There is always some human error. ... But it's pretty flat out there. Those narrow-front tractors aren't very stable."
Despite their easy-to-tip design, old tractors make economic sense for many agricultural operations. With new machines often priced at $100,000 or more, farmers can pick up a vintage vehicle -- with enough horsepower to get the work done -- for a tenth of the cost or less.
For Don Braun, who decided to get into farming at the age of 55 after retiring as a prison guard in St. Cloud, price was a major issue. He picked up several used tractors, the newest built in 1965, to raise crops on 120 acres that he and his wife purchased in Clear Lake. None of the tractors came with rollover protection.
"I bought what I could afford," Braun said.
Though he now rents the land to someone else, Braun -- who is 90 -- still lives on the farm and uses the tractors. In 2014, his 61-year-old son Brad used his father's 1952 International Harvester to move a 1,200-pound bale of hay. The machine tipped over, landed on him and killed him.
Don Braun said his son should have lowered the bale before driving it down a dirt road with a slight incline, but he was in a hurry to get out of town to go on a cattle drive.
"It was just carelessness," said Braun, who bought the tractor 10 years ago for $3,000.
It was the second time Brad rolled the International Harvester. The first accident left him with three cracked vertebrae, Braun said. Braun said his son's fatal crash showed him the value of rollover protection, since it likely would have prevented Brad from being crushed. But he said he can't afford it. Braun figures it would cost him about $2,400 to modify all three of his tractors.
Many farmers can't justify that kind of expense.
"You'd never get that much money out of it," said Braun, who intends to spend about $600 to repair the International Harvester that killed his son. "Maybe you save a life, yes, but I don't think it would be worth it for the amount of use they get."
There have been efforts to make it more affordable for farmers to install rollover protection. For example, New York created the nation's first and best-funded tractor rebate program in 2006.
On a dairy farm 50 miles west of Albany, Wayne Conrad operates 14 tractors, half of them without rollover protection. He used the program to modify two of his most-used machines, including a 1961 model that rolled while his brother was driving it in the 1970s.
"I've got two young boys, and I didn't want it to happen again," said Conrad, whose brother was not injured in the accident.
It cost about $2,000 to put rollover protection on the two tractors, but Conrad's cost was about $600 after rebates. New York covers 70 percent of the costs of adding rollover protection, with no maximum.
Conrad said the investment saved his life in 2008, when he was pulling a wagon full of oats down a hill. It was about to rain, and Conrad said that in the rush to connect the wagon to his upgraded tractor, he inserted the wrong pin. When the pin fell out, the wagon overtook the tractor and smashed into the back.
"If that roll bar wasn't on there, that wagon would have come up over the seat and crushed me," Conrad said.
So far, 14 farmers who have participated in the New York program have survived a rollover or other life-threatening incident on their modified tractor, according to program officials. Another 153 farmers reported "close calls."
"You never think it is going to happen to you," Conrad said. "I was one of those guys, too. But I got proven wrong."
Since 2006, about 1,400 tractors have been upgraded in the state. The program receives $250,000 in state funding annually, a fraction of the $5 million program advocates originally sought.
"It's not enough to get the job done, but New York state has invested way more than any other state has," said program founder May.
At the current rate, it would take more than 400 years to retroÂfit all 78,000 tractors that lack rollover protection in New York.