In every culture, there are certain expectations about personal space. If you are too near the person with whom you are interacting, you may be perceived as excessively intimate. If you are too far away, you may be perceived as too formal, uncaring, or emotionally distant.
How near should you be when you are interacting with Americans
The anthropologist Edward Hall studied personal space and found that Americans tend to favor a slightly greater distance than in many other cultures. For ordinary interaction with friends and acquaintances, Americans favor a distance of at least 2 feet (as for a handshake) and often as much as 4-5 feet. For more formal or business interactions, the distance may range from 4-12 feet. Within 18 inches or so of the person is reserved for intimate interactions: between very close friends, family members, and pets.