Definition
Urban decay is the visible deterioration of urban neighborhoods — vacant buildings, falling property values, departing employers, collapsing public services — produced by the interaction of disinvestment, racial segregation, infrastructure decisions, and policy choices over years or decades. It is sometimes presented as a natural process of city aging, but the historical record shows it is overwhelmingly the product of specific decisions made in specific rooms.
In The Power Broker the Bronx is the case in point. The borough's mid-century decline cannot be told without the Cross-Bronx Expressway, the segregated public-housing siting decisions, the redlining of mortgage lending, and the long withdrawal of city services that followed.
Why it matters
How it works
Urban decay compounds along a predictable chain. First, an infrastructure decision (an expressway, a public-housing project sited at a neighborhood's edge) physically disrupts the existing fabric. Second, banks and insurers reclassify the affected area as high-risk and withhold mortgages and policies — the redlining step. Third, employers move out to suburbs and exurbs to reach the population that left first, taking jobs with them. Fourth, the city, facing falling tax revenue, reduces services — sanitation, policing, fire protection — which makes the area less livable. Fifth, the resulting visible decay confirms the original reclassification and accelerates the cycle.
Each step looks individually rational from inside the institution making it. The system effect — a neighborhood that goes from working-class stability to vacant lots in twenty years — is enormous, and durable enough that the reversal often takes longer than the decay did.