The good news is that fewer people are driving while drunk or under the influence of alcohol. The bad news is that more of them are driving under the influence of marijuana or prescription drugs. This mixed news comes from the National Highway Traffic Safety Administration, which has issued the 2014 results from its Roadside Survey of Alcohol and Drug Use by Drivers.
About 8% of drivers were found to have alcohol in their system during weekend nighttime hours. Just over 1% were found to have 0.08 percent or higher breath alcohol levels, which is the legal limit across the United States. This is down by about 30% from the last time the NHTSA did this kind of survey in 2007 and down 80% from the first survey, done in 1973.
But as the alcohol levels drop, the incidence of drugged driving is rising. In the 2014 survey, nearly one in four drivers tested positive for at least one drug that could affect safety. The number of weekend nighttime drivers who had evidence of drugs in their system climbed from just over 16.3% in 2007 to 20% in 2014. The number of drivers with marijuana in their system rose by nearly 50%.
The National Roadside Survey is a voluntary, anonymous survey that gathers data at locations across the country. The survey is completely voluntary and the information collected is entirely anonymous.
The NHTSA conducted a second survey to see whether marijuana use by drivers is associated with a greater risk of car crashes. It found that marijuana users are more likely to be involved in accidents, but this may be because they tend to be in groups at higher risk of crashes. Marijuana users are more likely to be young men, a high risk group in general.