We all know someone who is driven to unspeakable rage by slowpokes in the left lane, and while their anger may not be healthy, this Vox explainer handily shows why they're not wrong. Not speeding (a little) in the left lane is really, really dangerous. While most people agree it should only be used for passing (and the law in 29 states mandates it), the danger of only going the speed limit in the left lane —or, god forbid, going 5 miles per hour slower—is much greater than you'd think. So, don't get angry, because that's also dangerous, but feel free to honk: