Informal and Friendly
Most people who come to the United States may already know a few things about the people through TV. Although this is of course a skewed reality some of the stereotypes are true, especially American friendliness and informality. People tend to not wait to be introduced, will begin to speak with strangers as they stand in a queue, sit next to each other at an event, etc. Visitors can often be surprised when people are so informal to the point of being very direct or even rude.