The number of pedestrian deaths is on the rise in Oregon, according to a new study by the Governors Highway Safety Association. Some evidence pins the blame on legal cannabis.

The study, which was first reported by the New York Times, notes that in seven states where marijuana has been legalized recreationally—Maine, Massachusetts, Nevada, Alaska, Colorado, Washington and Oregon—pedestrian deaths collectively increased by 16.4 percent the first six months of 2017 compared to the first six months of 2016.

In all other states reported, where recreational cannabis is not legal, pedestrian deaths decreased by 5.8 percent.

"Without making a direct correlation or claiming a definitive link," the study reads, "factors contributing to the increase in pedestrian fatalities might include the growing number of state and local governments that have decriminalized the recreational use of marijuana, which can impair judgment and reaction time for all road users."

In Oregon between 2014 and 2016, there were 198 total pedestrian fatalities. 29 of those occurred in the first six weeks of 2016. 35 occurred during the same period in 2017—marking a 20.7 percent increase.

Of all states studied, Oregon ranked number 14 for the steepest increase in pedestrian deaths during the six-week time period. (Washington D.C. was number one, with a 133.3% increase.)

A separate study conducted last year by the Highway Loss Data Institute concluded that the legalization of pot in Colorado, Oregon and Washington led to a roughly three percent increase in collisions claims.

Richard Retting, the author of the GHSA study, warns people not to confuse correlation with causation.

He told New York Times, "We are not making a definitive, cause-and-effect link to marijuana."

Retting added that people tend to drive more when the economy is good, placing more cars on the road, and that increased smartphone usage has created more distracted commuters.

Those factors could also be partially responsible for the increase in traffic deaths in Portland. According to a report released Tuesday by the Portland Bureau of Transportation, 2017 was the deadliest year for car crashes since 2003—with 45 people having died in collisions.

In response, PBOT has drafted a "Vision Zero" plan which includes $110 million to entirely rebuild a four-mile portion of Southest Powell Boulevard to make it safer for bike and foot commuters, and roughly $40 million to expand TriMet services.

The funding for the rollout of Vision Zero comes from a series of bills passed last year in the Oregon State legislature, aimed at improving street safety.

"Portland's streets remain challenging," says Bandana Shrestha, a Vision Zero Task Force member. "I'm encouraged by the work we're doing and look forward to the day when our streets are safe for people of all ages, no matter how they choose to get around."