We put a line on our maps to define east and west, but in reality everyone can be the east side to your location or the west... But i guess we usually mean by east as the 'primitive' side or undeveloped... so you find impulsive a priori norms, rather than sophisticated decisions.
"I am warning you, don't mess with my east side or you will get it all wrong!!!!"
The softer part of town where average-to-wealthy families reside. Usually is occupated by wangsters who think they are black or even better than the blacks of the West.