Car companies have accomplished something amazing over the 100-odd years since Henry Ford built his first eccentric horseless carriage. They’ve managed to make Americans feel downright deprived if they don’t have a car to zip around town in. (And yes, New Yorkers, we hear you, but most of us don’t live in cities where it’s actually harder to take the car than the subway.)

Those of us lucky enough to have cars get addicted to them. That’s how we end up doing absurd things like commuting 30 miles a day and then stopping by the gym, hopping on a stationary bicycle, and pretending to travel another couple of miles until we get tired and give up…because what do we need to be fit for, anyway? We can always drive.

Except, of course, when we can’t. Some of us don’t have cash for the car payments. Others recognize the ecological, fitness, and social values of supporting our local public transportation systems. Whatever the reason may be, you’ll surely find yourself on a bus or a train at some point—assuming that’s not part of your daily routine already.

And when you take public transportation, there are a few things you need to know if you want to avoid infuriating your fellow passengers. What sorts of things? We thought you’d never ask:

1. The Rule of Space

We’re not talking about black-hole and red-dwarf space (that’s for the public transit of the future), but personal space, that little bubble of air around your body that you definitely don’t want a stranger entering. Next time you hop on the train, give your fellow commuters what they want—room, and plenty of it.

Why are we so sensitive to strangers getting really, really close to us? Well, fairly recently, scientists discovered which portion of the brain is associated with personal space recognition: the amygdala. Turns out, it’s rather fond of others staying in their respective bubbles.

In a 2009 study, neuroscientists compared a 42-year-old woman whose amygdala had significant damage with 20 subjects whose amygdalas were just fine. According to ScienceDaily’s roundup of the research, not only did the woman prefer to be a whole foot closer to people than the healthy subjects did, but she never grew uncomfortable with closeness. The woman could be nose to nose with a complete stranger and not mind.

In a subsequent experiment, healthy subjects’ amygdalas lit up on brain scans when they thought the researchers were close by. Kind of like yours might when someone takes the seat next to you on the subway.

Interestingly, the amygdala’s spatial alarm system differs from one culture to the next. That is, when you’re traveling in a new culture, the rules about personal space might change.

Michael Brein, PhD, is a social psychologist who studies the psychological component of human travel—so much so that he bills himself as The Travel Psychologist. Brein tells FashionBeans how assumptions on proximity can differ from one place to another.

“There are cross-cultural/intercultural differences in behavior on public transportation,” Brein says via email. “One of the most notable differences is in spatial behavior: One person’s conversation distance is closer than another’s. There is great variation in what is acceptable and what is not acceptable in regard to conversation (and standing) distances between people. These distances vary within cultures and across cultures as well. …So what is normal for one person may be too close for another.”

No matter where you are, it’s always the best policy to avoid sitting right next to someone on the bus, if that’s possible. If you’re in a new city, keep your eyes open; do as the locals do.

“If we pay attention to our instincts and inner psyches, we’ll usually do just fine on public transit,” Brein says. “Observe, pay attention, and adjust accordingly.”

Here’s an extra tip: You are your bag. Your bag is you.

There’s an interesting corollary to the Rule of Space: Your stuff counts as an extension of your body. Smacking someone’s head with your backpack is just as bad as sitting next to them and relentlessly manspreading.

Adeodata Czink, an etiquette trainer at consulting firm Business of Manners, tells FashionBeans that “bagspreading,” to coin a term, is decidedly not good commuting form.

“Don’t take up two seats with your bag,” Czink says. “[And] don’t put your feet on the opposing seat.”

There are only so many seats available on the bus. Add to that the general discomfort with close proximity to strangers, and you’ve got a perfect storm of resentment for the bagspreaders of the world. When in doubt, keep your stuff on your lap.

2. Get in line (or get to queueing).

English-speakers outside of the U.S. don’t call that group of people, one behind the other, waiting to board the train a “line.” They call it a “queue,” which, in its gerund form, “queueing,” is notable for the absurd number of vowels packed in there, one after another—a veritable queue of vowels.

Anyway, no matter what you call it, there’s definitely a right way and a wrong way to queue up—and people are simply expected to know and follow these unwritten rules. If you travel to Asia, Russia, or the Middle East, you may find a very different approach than the one you’re used to.

In some parts of the world, the orderly queue can be replaced by an everyone-for-themselves mass of humanity. Countries with large populations, limited resources, or both, often have to abandon the idea of standing in lines.

“In some countries, e.g., the UK, people stand in lines,” Brein writes. “It is not okay to get in front of another person who is waiting in line [in these countries.] In other countries, all pandemonium breaks loose. People crowd the entrances of transit to get in. There is no rhyme or reason to it; it’s catch as catch can, and it’s okay!”

Meanwhile, nations that do embrace the queue might have subtle differences in what is and is not considered socially acceptable. In China, for instance, you can hire specialists to wait in lines, though not public transit lines, for you. (“You don’t need any skills,” professional line-waiter Li Qicai told NPR in 2011, “except the ability to suffer.”)

It’s important to recognize the cultural environment you’re in when it comes to waiting to get on or off of public transportation. In larger cities, where lines don’t cut it, finding a spot in a subway car or actually making it through the doors at your stop could be a serious challenge.

3. Spock’s Rule

If you’ve seen Star Trek IV: The Voyage Home, you know where we’re headed with this. If not, check out the clip below:

Everyone on the same page? There’s a reason the bus riders applaud the visiting Vulcan for nerve-pinching the punk rocker with the blaring boombox. In the 1980s, annoying loudness mostly came from punk rockers with boomboxes; today, it comes from just about anyone with a cellphone.

The good folks beside you on that bus don’t want to hear your music, not even if it’s an awesome faux-British-punk song called “I Hate You.” They also don’t want to hear your loud conversations on speakerphone.

“Don’t talk so loudly on your cell that everyone in the bus can hear it, whatever language you speak,” says Czink. She’s an etiquette trainer, folks; you’d better listen to her.

If you don’t, just watch out for tall guys with pointy ears. They’ve been known to silence loud passengers in the not-too-distant past.

What if you’re the one who’s freaking out?

Remember our first rule, the Rule of Space? Well, even if you don’t violate this rule yourself, you might end up falling victim to it. When your sense of personal space is invaded, your brain kicks into action, creating a potent—and potentially awful—sensation. That’s your brain trying to create a physical response, in hopes you can move and find a more comfortable situation.

Sometimes the very nature of public transportation challenges our personal space preferences. If you’re in a big city, there are going to be certain times throughout the day where people are packed into buses or trains. These situations can be especially stressful for individuals with anxiety.

There’s good news, though. If you struggle with commuter anxiety, there are ways to constructively handle your fears. Having a distraction during the ride, and using this time to practice mindfulness (in the forms of breathing and meditation) are great ways to reduce stress, according to a blog post by New Zealand-based psychotherapist Kyle Macdonald.

Failing any of that, you can always console yourself with these facts from the Federal Transit Administration: Light rail systems create 62 percent fewer greenhouse gas emissions per passenger mile than traditional gas-powered cars, and busses pump a respectable 33 percent less.

Even if you’re wedged into a bus stuffed full of manspreading punk rockers with boom boxes, you can travel with the assurance that you’re doing the planet a favor. That’s more than you can say for the horseless carriage.