Income segregation, income inequality and mortality in North American metropolitan areas

There is a large sociological literature on racial- class-, and economically- based segregation in the United States and there is some evidence that residential segregation by income may have deleterious health consequences for residents of large U.S. cities. The health consequences of segregation in Canadian metropolitan areas, however, remain unknown and the comparison with the U.S. is always compelling. In this paper, we investigate the hypothesis that residential segregation by income may be associated with mortality in Canadian and U.S. metropolitan areas. Given the strong relationship between individual level socioeconomic status and health, it follows that metropolitan areas which isolate individuals economically could produce conditions that severely limit the life chances and therefore the health chances of the most vulnerable. To investigate the association between residential segregation by income and population health, we examined the relationship between working-age mortality and Jargowsky's (1996) neighbourhood sorting index (NSI) for a large group of North American metropolitan areas. We found a relationship between increased segregation and increased mortality for U.S. metropolitan areas but no such relationship for Canadian metropolitan areas. We also determined that income segregation could not be considered in isolation from income inequality – that, in effect, income inequality provides the propensity for meaningful segregation to occur. We further demonstrated the importance of considering both income inequality and income segregation together, especially when the analysis is intended to compare metropolitan areas. We conclude with a discussion of the need for an improved measure of segregation to better reflect the theoretical arguments for the relationship between concentration of poverty and affluence and population health.