Traffic accidents have been a major cause of death in the United States since, well, the advent of traffic. But now, the Centers for Disease Control and Prevention have released data revealing that traffic fatalities are, for the first time ever, outnumbered by deaths from drug overdoses. It's not illegal drugs like heroin, methamphetamines, or cocaine that are leading this grim rise in deaths: It's prescription drugs. Here, a brief guide:

What are the numbers?
According to the CDC, drugs killed at least 37,485 Americans in 2009, compared to 36,284 deaths caused by traffic accidents. The death toll from drugs now claims one life every 14 minutes, even as deaths from other causes are dropping. 

What kinds of drugs are causing this increase?
Most are popular prescription painkillers and anti-anxiety drugs, many of which have become household names like Xanax, OxyContin, and Vicodin. These drugs now cause more deaths than heroin and cocaine combined. One relative newcomer to this group is Fentanyl, a pain medication that's 100 times more potent than morphine, and is available as a skin patch or as a lollipop.

Who's overdosing on prescription drugs?
Everyone. According to the Los Angeles Times, overdoses occur among elderly Americans who take several drugs for multiple conditions; teenagers partying with their friends; and middle-aged working men and women who take painkillers for strained backs and bum knees.

Is driving safer than it used to be?
Much. Seat belts, air bags, and other automotive safety features have made driving much safer than it once was. Traffic fatalities have dropped by more than one-third since the early 1970s, even though more American drivers are logging more miles on more roads. Meanwhile, deaths tied to prescription drugs have doubled over a 10-year span.

Sources: Los Angeles Times, Newser, RedOrbit