Had my personal space breached yesterday while in the checkout line at Publix. Was waiting my turn, and giving the woman in front of me reasonable space because it was her turn.
The guy behind me started unloading his groceries on the conveyor, behind mine, because I put the separating bar on it after I finished putting my stuff up.
As I stood up straight from my cart, I backed up right into him, hard. Turned and sweetly said, "excuse me". He stopped encroaching. Then I had to listen to him bitch because the cashier and the woman in front of me, weren't moving fast enough for his liking. I turned, smiled, and said, "We'll get there." I really wanted to cuss him out, but I decided to kill him with kindness instead. I think I've lived in the South so long, some of it has rubbed off on me. I can say, "bless your heart" and make it sound like "go fuck yourself".

It's definitely a cultural issue. I've worked in countries that didn't have the same sense of space that I do, and it is a little bewildering. I remember in the market in Bamako, when I showed interest in some hand-dyed cloth, I was suddenly inundated by women with similar wares. They (several at once) took my arm the way no one would a stranger in the US, trying to lead me to their booths. It was strange, and sweet, and interesting, all at the same time. I did not feel the least bit threatened, but I was bemused by their willingness to get close to someone they'd never seen before.

PS: I bought cloth from the original vendor, who jumped right in there to keep me.

My personal space is fairly small, but I hate like heck when your semi-erect penis pushes into my back. Makes me turn around and spit in your face. Munich, street car 1972 - you know who you are!

I don't like crowds, never have.

One cannot travel as much as I have and come out still concerned about personal space. I recognize there are differences in various cultures and pay heed to their standards, but I'm no longer upset when someone invades what I used to consider 'my space'.

On the other hand, if it is apparent someone is attempting to intimidate, they discover rather quickly that it isn't working -- and I don't need to say a thing.

I’m an introvert. So personal space is important to me. Invading my personal space makes me extremely uncomfortable.

Yeah I don't get it. Especially when you're on a train or bus and there are 25 empty seats, but someone sits right next to you. I just move.

I try to keep a goodly amount of space with strangers. Less with people I know and with people I really like we touch. Crowded elevators, buses, trains, etc. I can do this energy thing that seems to keep people from pushing in too close. As to 'close talkers', large people - tall/big men in particular- who get in your face do this to intimidate. trump stalking Hillary. There was a commissioner in the county here who would do this with people who questioned him on issues. Bullies do this alot. Cultural differences are another story.

depends on how tired I am, but I live in the burbs and drive my own car.

I don't give a damn.

I worked with a fellow who didn't have any sense of personal space. He (like I) worked in the Psych Field. I could not understand how he'd never been pummeled by a client.
We took a self-defense course together and I wanted to hit him. I mean he could be trying to walk through you and was still not aware? Baffling.

I move, unless there is some advantage to be gained by staying, such as being first to board or whatever.

I don't get bothered unless I think someone is purposely trying to get close to my body because they want to be close to my body. That doesn't happen often. I realize that size and awareness of personal space buffers vary widely, even in the same culture. I just move if I need more space.

Don't you dare give me the evil eye if I move away from you, as if my having different personal preferences is an indictment of yours. Don't shame me for where my comfort zone dials are set. It's my thermostat, dammit. I'll set it however I please.

It is a cultural thing. Some cultures are used to being very close to someone when talking or interacting with them. Personal space varies with different cultures.

If there are any weird odors coming from within a 20 foot distance, I move no matter what. Some people are just not aware of personal space. So strange. But there are cultures where personal space isn't even thought of.

Under the conditions you've described, personal space is needed.

Danger! Security breach! Engaging farton torpedoes...

Admittedly, I encroached on someone else's personal space a while back.

The benches at the station have middle arm rests that divides them to 3 seats - to discourage people lying across them. A man walking just in front of me arrived at a bench that I was going to sit on. But he sat in the middle seat. There are no other benches at that end of the platform.

Usually, I would ignore it and wait standing up. But the episode of Curb Your Enthusiasm in which Larry David asked a woman why she chose to sit on the middle seat was on just the previous night.

So I did kind-of the same. I sat in one of the outer seats, put my elbow on the inner arm rest, and slouched towards him. He was on the phone all this time, by the way. Eventually, he got up and moved elsewhere.

I work on personal space issues in others as part of my daily work life. I have acknowledged that my personal preference is possibly 3-4x what people typically need or want. Mine could even be measured using football fields.

Yeah, it bothers me a lot. I'm gonna give a wtaf look and move away, probably with an audible sigh.

It can definitely be a cultural thing. Look at some Asian cultures where stuffers are used to cram as many people as possible on to trains.

As long as they don't try to lift my wallet or phone I don't really care. Who knows, maybe they just think I'm sexy. Lol