Wait, you're Canadian now? Weren't you Basque in Spain?
You're talking about some drug epidemics, like heroin (prior to it becoming a suburban problem in more recent years) and crack.
"zone divisions" would be getting shunted into inner city slums or housing in less desirable areas of neighborhoods and towns. Plus red lining, which would be discriminatory lending practices for businesses and homes. Then there's gerrymandering for voting districts,,,