The earnings difference between white and Black workers fell dramatically in the United States in the late 1960s and early 1970s. Claire Montialoux, in a paper with Ellora Derenoncourt, shows that the expansion of the minimum wage played a critical role in this decline.
Recommendation:
"The Color of Law: A Forgotten History of How Our Government Segregated America" by Richard Rothstein
https://www.goodreads.com/book/show/32191706-the-color-of-law
Paper:
"Minimum Wages and Racial Inequality" by Ellora Derenoncourt and Claire Montialoux
https://academic.oup.com/qje/advance-article/doi/10.1093/qje/qjaa031/5905427?searchresult=1