I live in a growing suburban area, but for the most part there's still this small town feel to a lot of the area. You would think this general level of friendliness with the people you meet would mean at least a moderate amount of eye contact, but really I find that there is little eye contact here, even with the people you are relatively close to.
I had the opportunity to spend a year in London and I found I was a little startled at first when people would make eye contact with me. While its true that Londoners are in general rather private and don't make conversation while on the Underground I don't think that makes them unfriendly or uncommunicative. On the contrary, I thought that they utilized eye contact as a way of communicating (thats actually how I got my first date over there, hehe ) a lot more than Americans and while London is a large city their personal space is also a lot smaller. I remember one time when one of my professors came over to talk to me I actually took a step backwards before I could stop myself simply because I was used to having a larger distance between myself and the person I was talking to then she did.
Despite their lack of spontanious conversation I also found the culture their endearing simply because of the way they speak and greet the people they do know. For example, my friends and I adopted the custom of a kiss on both cheeks when we saw each other. This is rather intimate as you get right up into the other person's personal space. Also, at my local Waitrose shopping market the cashiers would always say something like, "How are you today my love?". Its these little intimate gestures and expressions that make me really miss London.
I think the amount of eye contact has more to do with culture then the level of population, though I'm sure that is a factor too. This is just a thought and I have no real proof to back it up but I think in general Americans are less trusting then people of other nationalities which might explain the difference in the use of eye contact and the amount of personal space here as opposed to the UK or Canada.
My sociology professor told my class how at a dinner party while he was talking to someone he would take a half step forward every once in a while and eventually backed the guy up all the way across the room. It would be interesting to try a similar thing with eye contact. The next time you meet someone try and look them right in the eye during the course of the conversation and see what they do. Do they try and look away? Do they find a way to end the conversation quickly? Do they increase the amount of space between the two of you? Can you tell I'm a psych major? lol