However, Katzman finds that in Detroit by the 1880's the old elite began to give way to a middle-class business leadership with its roots in the black community. The new leadership, which stressed racial identity and self help, appeared before large-scale migration from the South. The author argues that the pressures of caste, the dying out of the old elite, and an aggressive spirit among blacks caused this shift, not the presence of an enlarged market. Despite the transformation of Detroit's economy brought on by large scale industrialization between 1870 and 1910, Negroes remained concentrated in the same marginal and low-paying service occupations. The author mentions the importance of illegal en- BOOK reviews191 terprise among blacks blocked from other avenues of opportunity but does not develop the point. Blocked opportunity prevailed in politics as well. In the 1870's and 1880's, upper-class blacks benefited from the close association between the Republican party and Negro