Uptown/downtown and right/wrong side of the tracks are distinct patterns of economic geography based on the form of long-distance transportation the city grew around.
For shipping, the city grows around a harbor and eventually industry and commerce grows up in the sea-level area around it (“downtown”) while acceptably low-density, high-wealth residence expands into the higher-elevation (“uptown”) hinterlands
Railroads allow inland towns capable of 360\u00b0 growth, the pattern there is for industry (and subsequently working-class residences) to grow away from the rails in one direction and commerce and administration (and thus middle-class residences) in another
I suppose suburb/inner city is the equivalent pattern for the highway era.
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