ROBERT SIEGEL, HOST:
Ari, let's talk about your driving.
ARI SHAPIRO, HOST:
Oh, not my driving. I bicycle to work.
SIEGEL: All right. All right. But when you are behind the wheel, here's something to think about. If you are ever the guy in the left-hand lane slowing down traffic, stop it.
SHAPIRO: OK. This is something we've been talking about since we saw a piece in Vox by freelance science reporter Joseph Stromberg. He stresses the science on all of this is not settled, but...
JOSEPH STROMBERG: When you're traveling on the highway, the moment at which you're most at risk of getting into a crash is when you're changing lanes. And when you have people going slow in the left lane, as well as the right lane, then people who want to move faster kind of have to zigzag back and forth. They have to change lanes looking over both different shoulders, and it just increases the amount of possible accident scenarios that can happen.
SHAPIRO: Every state has laws that discourage left-lane driving, and some, including Ohio, Texas and Washington, are handing out tickets.
SIEGEL: But wait a minute, you might be saying to yourself. I'm going the speed limit. I can't be the problem. Oh, yes, you can. Here's Stromberg again.
STROMBERG: One of the best predictors of an accident isn't necessarily whether someone's speeding or not, but the difference between the average speed of traffic surrounding them and how fast they're going. And it turns out that going 5 miles per hour slower than the surrounding speed of traffic puts you at a greater risk of accident than going 5 miles per hour faster.
SHAPIRO: And slower drivers can mean more traffic jams.
STROMBERG: There is, you know, strong research showing that just a small amount of congestion can ripple outwards and make a really big traffic jam. And a lot of times that's because of just a few cars that are going slower than the speed limit or just at it and blocking up both lanes. And that causes, you know, layers and layers of people trying to pass just backed up behind them. And so it's annoying, but it also really can cause legitimate congestion.
SHAPIRO: So if you're driving this Labor Day weekend, let the lead foots have the left lane.
SIEGEL: You'll be doing everyone a favor.
(SOUNDBITE OF SONG, "LONG LINE OF CARS")
CAKE: (Singing) But this long line of cars is trying to get through. Transcript provided by NPR, Copyright NPR.