Maybe in 20 years we won't need this article, because we'll all be passengers in self-driving cars. But until computers take the driver's seat, human drivers need to understand the rules of the road.

One rule I see most egregiously ignored, especially on the West Coast — California, Oregon and Washington state, where I've lived in recent years — is drivers who hang out in the left lane when they're not passing another vehicle. I've driven between San Francisco and Portland, Oregon a dozen times and up to Seattle as well. I've also done trips from San Francisco to Los Angeles and out into the desert to Joshua Tree and to the Salton Sea. It's common to see cars and SUVs just drive for 50-plus miles in the left-hand lane, not using it as a passing lane, and often going at or below the speed limit.

In this scenario, those cars wanting to go the speed limit are forced to pull over to the right lane, pass the car dawdling in the left lane, then get back into the left lane to pass the people who are (correctly) driving slower in the right lane.

It is maddening. And dangerous. My last drive up to Seattle from down south on Interstate-5, a major corridor, saw me carefully weaving in and out of lanes for hours to maintain the speed limit. I counted, and in an hour I had passed 52 cars on the right, and 47 cars on the left.

That's not just annoying, it also impedes the flow of traffic, leading to jams and slowdowns for everyone. Both of these situations are directly caused by those checked-out drivers who are hogging the left lane as the video below explains.

Yes, it matters (and by the way, it's the law)

I've been back in New York and Connecticut for a few weeks now, and I've found that left-lane-dozing is much less common on this side of the country. Perhaps it's because the roads here tend to be markedly smaller (lanes aren't as wide, and shoulders are skinnier), so people are forced to pay closer attention to their driving. And there's a lot more communication between drivers via the turn signal here, too. Or maybe it's because if a driver is dallying in the left lane, it's absolutely part of the driving culture in the New York tristate area to pull up behind them, flash your lights and even beep your horn to encourage them to move into the right lane. If that happens to you enough times, you learn to use the left lane for passing only.

It isn't just polite or good driving to use the left lane for passing — every state has a law about it, with some subtle variations. In Hawaii, you aren't allowed in the left lane at all if you're driving more than 5 mph below the speed limit; in Rhode Island, you can get in trouble for passing on the right. In Georgia, it's a misdemeanor to drive in the left lane more slowly that surrounding traffic, and Tennessee is now regularly issuing fines for slowpokes in the left lane.

These rules exist because, as state Rep. Dan Howell told the Chattanooga Times Free Press: "It’s not the speed on the highway that kills as much the weaving in and out of traffic, which is caused by people who impede the flow of traffic." Howell was the sponsor of a Tennessee bill to fine motorists who use the left lane for everything except passing.

Slow drivers might think they're being safer by driving below the speed limit, but that is a false equivalency. There's a difference between going with the flow of traffic and speeding dangerously (which does cause accidents). And distracted driving is the number one cause of accidents — not speed.

The proof is in the pudding — or actually the autobahn, which I've also driven on. When drivers pay more attention to their driving, there are fewer accidents, even if theyt are hurtling along at 90 mph. At those speeds, you have to be actively driving at all times, and it's statistically safer.

I have nothing against people who like to drive more slowly for whatever reason. Just please, keep right and let the rest of us through.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.