Pedestrian fatalities in the US reached a 30-year high in 2019, according to a new study — and the researchers believe smartphones, an increase in SUVs and marijuana legalization are behind the spike.

An estimated 6,590 pedestrians died in car crashes across the country last year, according to the study released Thursday by the non-profit Governors Highway Safety Association — a 5 percent increase from 2018, and 60 percent spike since the number began to rise in 2009.

The last time pedestrian deaths were that high was 1988.

The man behind the report thinks increased smartphone use is the primary culprit.

“For 30 years, pedestrian deaths were declining. Something changed in 2009,” said researcher Richard Retting of the Sam Schwartz Engineering firm, who wrote the study. “What happened in 2009 that reversed that trend? I don’t see any other factor.”

Both pedestrian and driver distraction may be at play, but the extent to which one or the other is a greater problem is not clear, he said.

“Drivers have gone way beyond just texting, but have cellphones mounted on their windows and dashboards. They’re watching movies and baseball games,” Retting told The Post. “We were basically creating an environment where people who are taking their eyes off the road for seconds at a time are traveling hundreds of feet in that time.”

Retting’s conclusions are based on preliminary data from the first six months of 2019, which he extrapolated to make an estimate for the rest of the year.

Among the other possible explanations for the surge in deaths offered by the researchers — the growing popularity of SUVs and warmer temperatures drawing more pedestrians out after dark, when fatality rates are significantly higher.

The report also suggests “changing patterns in drug use, including decriminalization of marijuana” as a possible cause, though provides no evidence.

A whopping 47 percent of the pedestrians deaths occurred in either Florida, Georgia, Arizona, California or Texas — all states whose suburban populations are booming, putting more and more people in areas prone to faster driving.

“It’s a national crisis, and the fact that 300 more deaths occurred last year than the year before is a shame on this country,” Retting said. “We are in crisis mode.”