Why Are the Western Ends of Cities Generally Wealthier than the Eastern Ends of Cities?
Dan Zambonini alleges that cities in the northern hemisphere tend to have poorer eastern rather than western sides. He then suggests that this is because wealthier people could afford to be upwind of air pollution:
Many older cities rapidly expanded during the Industrial Revolution, as workers flocked to the urban centers. As the towns and cities expanded, the residential areas for the workers tended to be in the east, with the middle and upper-classes in the west.
The reason for this is that in much of the northern hemisphere, the prevailing winds are westerlies – blowing from west to east. The massive, unchecked pollution from these early industries would therefore drift eastward, making the air quality much lower in the east end of cities, lowering the desirability (and price) of the housing. Middle classes preferred the cleaner west ends.
The issue was probably even pre-Industrial Revolution, as smoke from personal chimneys would still have caused problems to the east.