I've been to the US several times as a tourist and have observed some noticeable things about my fellow countrymen.
1. We now realized the difference between the red, amber, and green lights.
2. We also began to understand that the striped lines along the road is where the pedestrian crossing is.
3. We learned how to greet other people, look straight in their eyes, and say "how are you doing?".
4. We learned how to pay taxes properly.
5. We now understand that flashing our headlights means "I'm letting others pass first!" and not "hey, make me pass first"!
You may add your observations too!