When my mom came to visit Chicago a few weeks ago, she said, "You know what the biggest difference is about a city? People don't look you in the eye." It's so true! I thought about it last night as I was walking home from work. You don't want to look people in the eye because of 1) safety 2) you're avoiding a bum asking for money or 3) you're avoiding getting asked to donate money for a cause.
When I first moved here, I kept true with my Wyoming self and looked everyone in the eye and I would either smile or say hello. After a few strange looks from women, or creepy men who thought I was hitting on them and winked at me in response, I thought I probably should stop this. Now I realize, after a year in Chicago, I really don't look anyone in the eye.
I've also stopped saying "excuse me." In Wyoming, if you're in someone's way or you accidentally brush up against them, you say "excuse me." So for the first few weeks in Chicago, I was constantly telling people this. But here's the thing...in a city, you will ALWAYS been in someone's way. You will have accidental collisions everyday. Sometimes you will have to bump into someone, or accidentally step on their toes on the L train, but people don't take it personally.
A third change I've noticed is that I used to be so bothered when someone walked or stood super close to me on the streets or in line at a clothing or grocery store. I used to take it personally, like they were trying to be rude or get me out of the way. I've come to realize they don't know any differently. They've been in a busy city their whole lives, so they are used to being in close proximity with other people.
All-in-all I would say Chicago has made me a much more patient person. When you're stuck in traffic or behind a slow person, you can either choose to get really annoyed, or just take a deep breath and realize it's the price you pay to live in a really cool city.