Way back,  I asked rhetorically why the 'poor' side of town was inevitably located either in the south or the east.  And over my vacation break I read something in Harper's Magazine that finally answered my question:

from A Wire Story by Michael Martone, Harper's Magazine, May 1999, p. 34

"Fort Wayne, as in many Midwestern industrial cities, the factories were built on the east side of town. The prevailing winds are from the west, and thus the location of a city's smokestack industry is downwind."

Makes sense to me.