Any time Mary Gaston drives by the intersection where a driver high on marijuana plowed into her son’s motorcycle two and a half years ago, the loud bang of the impact replays in her head.

Blake had hugged her before he left the suburban Seattle restaurant’s parking lot — it was the last time she would ever feel his embrace.

“I heard it and I knew instantly,” Gaston remembers. “I said ‘that’s Blake’ and I just ran. It was not even 50 feet away. And he was lying in the intersection bleeding out.”

Though doctors tried to save his life, 23-year-old Blake Gaston didn’t make it.

His story is becoming frighteningly more common. A new report by the American Auto Association (AAA) has found that the percentage of drivers who are high on pot during fatal accidents in Washington State more than doubled between 2013 and 2014.

Open vintage shredder and bag with medical marijuana; Shutterstock ID 414208561; PO: today.com; Other: claudia Maxim Apryatin / Shutterstock

In Washington, only looking at crashes in which at least one driver tested positive for active THC, there were 40 fatalities in 2010, compared to 85 in 2014, according to AAA estimates. However, a large number of drivers were not tested for THC or did not have available blood test results, so THC-related fatalities could be much higher, the report notes.

The AAA report focused only on Washington state, while legalized the sale and possession of marijuana in 2012. It did not track driving while high fatality trends in Colorado, which also legalized pot that in 2012.

But with marijuana on the ballot to become legal in more states, AAA researchers fear that the numbers will rise more sharply.

The problem is, many people don’t realize that “driving under the influence” isn’t just about drunk driving. It also means driving when you’re high.

“Driving is already a tough task,” says Jake Nelson, director of Traffic Safety Advocacy and Research at AAA. “When you add a drug that impairs our ability to manage that task, it’s a recipe for disaster.”

Currently 20 states allow medicinal marijuana use, while four states and Washington, D.C., allow recreational use.

Related: Pot fuels surge in drunk driving deaths

After the accident, Mary Gaston learned that the driver of the car that hit her son’s motorcycle, 33-year-old Caleb Floyd, admitted he had been smoking pot. He was eventually convicted of vehicular homicide and sentenced to three years in prison.

That’s little comfort to Mary, who wonders where her bright, talented son would be now if he not been hit by a stoned driver.

A computer whiz who developed websites, Blake was also an accomplished musician.

By 23, he'd already mastered numerous musical instruments, including piano, guitar and drums. He didn’t just play music, though, he also wrote songs too.

“Blake was going to change the world,” Gaston says. “Blake had an energy about him. He affected people’s lives in such a positive way. It makes me happy to think about him. Even in 23 years he lived a hell of a life. His life was way too short. But he lived a hell of a life.”