The purpose of this dissertation research is to determine the causal relationship between local roads spending (i.e., state-allocated road spending and locally-raised road spending) and the decentralization of people in the context of the Detroit Metropolitan Area between 1980 and 1990. This research adopts a human ecology methodological framework and develops a conceptual model that broadly integrates local roads spending with proposed explanations of decentralization. The conceptual model is developed within social geographic inquiry and is informed by three perspectives (a) ecological and spatial assimilation, (b) neighborhood preference, and (c) place stratification in understanding the decentralization process. This research integrates each of these three proposed theoretical perspectives into the human ecological framework to conceptualize how local roads spending affected decentralization during that decade.

A standard multiple regression and spatial regression approaches were implemented to estimate the effect of local road spending on decentralization. Three models were estimated using three different measures of decentralization as the dependent variable in these models, including: (1) percent change in general population density; (2) percent change in the relative concentration of non-whites; and (3) percent change in population density of non-whites. The first dependent variable measured the pattern of decentralization in the general population and the latter two dependent variables measured the non-whites' pattern of decentralization.

The dependent variables were each regressed against a lagged value of state-allocated road spending at the municipality level controlling for local road stock, distance from the central business district (i.e., downtown Detroit), household median income, percent college educated non-whites, percent of the non-white population, and proportion of white to total homeowners.

The result from the first model (i.e., percent change in general population density) indicated that state-allocated road spending had a significant effect on decentralization (β = 0.56, p < 0.10). The result from the second model (i.e. the percent change in the relative concentration of non-whites) indicated that locally-raised road spending had a significant effect on decentralization (β = 1.76, p < 0.001). On the other hand, the results from the third model (i.e., percent change in population density of non-whites) did not indicate significance of either state-allocated or locally-raised local road spending on non-whites' decentralization. Other variables that were important in all three models of decentralization were percent non-whites and distance from the central business district. These findings show that both state-allocated and locally-raised spending were important in decentralization in the Detroit Metropolitan Area but the populations impacted varied. While future research should continue to investigate the effects of both spending on racial differences in decentralization, the study recommends an emphasis on the state-allocated road spending mechanism and its policy implications.