On Friday and Saturday nights, according to roadside surveys conducted by the National Highway Traffic Safety Administration, one out of five drivers has a drug other than alcohol in their system.
The agency says the drug that showed the greatest increase between 2007 and 2014 was marijuana.
The National Institute on Drug Abuse says after alcohol, marijuana is the drug most commonly involved in crashes.
Despite this, some argue marijuana does not necessarily make a driver unsafe.
Like one San Diego woman, who asked us not to use her name because she does not want her boss to know she smokes pot. She said marijuana makes her a better driver.
“I think it’s just because the weed makes me feel much more relaxed, and I don’t feel rushed, because most of the time I feel rushed just because the nature of my job,” she said. “But when I’m smoking weed, I can go whatever pace I want to.”
But others could smoke the same amount of pot as this woman and feel totally out of it.
So when does someone cross the line and become impaired? Researchers at UC San Diego are trying to find out.