It's the last holiday weekend of summer and to millions of Americans that means one thing: Getting stuck in a brutal traffic jam on their way to whatever getaway they have planned. The sad thing is, it doesn't have to be this way. Not that there wouldn't be traffic jams, but if most of us drove just a little bit differently, they would be a lot fewer of them.

Traffic jams result at least in part from what social scientists call "the tragedy of the commons"--the phenomenon in which a group individuals each act in their own best interests, making everything worse for the entire group, including themselves. Most traffic jams are just one big tragedy of the commons.

Here are just a few things drivers do to try and get where they're going faster that winds up making traffic much worse than it needs to be. Do you do any of these things? I have to admit, I've been guilty of at least a couple myself.

1. Driving in the left lane when you aren't passing.

Of all the behaviors that make other drivers crazy, this may be the one that causes the most ire. It may seem to you that you're entitled to drive in the left lane so long as you're going at least as fast as the speed limit, but experts--and the law in most states--disagree. Most states have some law governing use of the left lane. The strictest say you can only use the left lane to pass or turn left. Most say you must get out of the left lane if you're going slower than the flow of traffic, whether you're driving at the speed limit or not. Only a handful say that you can use the left lane if you're going at least at the speed limit.

There's a reason for these laws. Research consistently shows that a surprisingly small number of cars going slower than the rest of the traffic leads to traffic jams and increases the likelihood of accidents. You may think you're making things safer for everyone by driving at a reasonable speed in the left lane and preventing the drivers behind you from going at dangerous speeds, but it just isn't true.

2. Changing lanes to try and get ahead. 

It's incredibly tempting, I know. You're sitting in a lane that's come to a complete standstill, and the lane to your right is moving slowly, but it is moving. Every instinct you have is telling you to pull one lane to the right.

Be strong--resist the impulse. The most likely reason your current lane is at a standstill is because just a little ahead of you, a number drivers just like you noticed your lane was moving faster, and so they all changed lanes into it. By switching out of it, you exacerbate the problem because every time someone changes lanes in heavy traffic, it causes cars to slow down.

I can personally attest to the benefits of not changing lanes except when entering or leaving the highway. Five years ago my husband and I moved from New York State to Western Washington, and we were both immediately struck by how much more polite and collaborative drivers are in the Pacific Northwest. One of the biggest differences that I've observed is that Washington drivers change lanes much, much less often. And, yes, it makes a huge difference. Earlier today, I was driving into Seattle in very heavy traffic. But here, most drivers stayed in their lanes, and the entire group of cars was traveling down I-5 at 70 miles an hour. If everyone had been constantly changing lanes, maneuvering for a better position, that simply wouldn't have been possible, and it would have taken at least twice as long for all of us to get where we were going, probably in bumper-to-bumper traffic. To put it another way, it would have been like driving in New York.

3. Not leaving a large enough space between your car and the car in front of you.

We all know tailgating is bad. But beyond that, there's an optimum distance between cars that we all should be maintaining, and most of us aren't. Keeping a little more distance between your car and the car in front of you benefits everyone because if the car in front slows down unexpectedly, you don't have to slam on your brakes, which means the driver behind you also doesn't need to slam on his or her brakes, and so on. 

Leaving plenty of space in front of you, incidentally, also allows other drivers to change lanes into that space without slowing the flow of traffic. Yes, that means sometimes people will pull in front of you and get where they're going a fraction sooner than you will. But it's still true that leaving that space will help speed the flow of traffic and benefit everyone in it, including you.

4. Not maintaining a consistent speed.

This is something I'm occasionally guilty of, and it's one of my husband's biggest pet peeves. It's obviously not possible to maintain a consistent speed if a car in front of you slows down abruptly. But if that car speeds up again, and you zoom ahead to catch up, then you're likely to have to hit the brakes again when you get there. This style of driving makes your car burn gas faster and increases the wear and tear on both your brakes and your engine. It's less safe than driving at a consistent speed, and considerably less pleasant for any passengers you may have. And it contributes to traffic jams for the same reason tailgating does: When you brake hard the driver behind you has to as well, so does the driver behind them, and so on.

So it'll be better for everyone, and for your car, if you do what you can to maintain a consistent speed in traffic. And here's the easiest way to achieve that: Stay out of the left lane except to pass, don't change lanes when you don't need to, and keep a sizable distance between you and the car ahead of you. If we all did all of those things, holiday weekend traffic would be much easier to bear.