Affirmative action built a persistent black middle class and aided the least skilled

Evidence

Aggregate analyses of employment suggest that affirmative action did target blacks during the 1970s, and that it contributed to the creation of a substantial black middle class that has persisted over the succeeding three decades. … Affirmative action did not, moreover, target only those already well-educated or in the middle-income brackets; its initial effects were greatest for people in unskilled and semiskilled job categories (Leonard, 1984b). … There is no evidence that affirmative action policies have harmed productivity of participating firms (Leonard, 1984c). — David Theo Goldberg, John Solomos, A Companion to Racial and Ethnic Studies, 1973

Categorization

• XREF: Connects to the recurring claim that affirmative action’s benefits went mainly to already-educated elites — this study directly contradicts that assumption.
• QUESTION: Which specific studies showed greatest effects for unskilled/semiskilled workers, and why did that effect fade in later decades?