Um.... When you increase the minimum wage, you limit the ability of employers to hire people as the price becomes too high. Before the minimum wage it was easier for employers to hire Blacks at the lower wages than to higher Whites, who preferred the higher wages. When the minimum wage was instituted, the higher wage applied to both Whites and Blacks and Blacks lost the advantage of being more employable at the lower wages. With more competition against Whites and contemporary racism Blacks weren't able to get the jobs that Whites got.