This is a study of modern slavery.
Slavery - Wikiwand
Contemporary slavery - Wikiwand
Slavery among Native Americans in the United States - Wikiwand
Slavery among the indigenous peoples of the Americas - Wikiwand
Slavery in Africa - Wikiwand
Munger on Slavery and Racism | EconTalk | Library of Economics and Liberty
Equality: Montesquieu, Spirit of Laws, bk. 15, CHS. 1, 4--8
The British banished slavery in the late 18th centuries, however slaves are of higher demand for laborious works in the southern parts of the States, which finally lead to the Civil War.
The slave masters have to come up with reasons for keeping slave. This marks the beginning of the allegation that the African blacks is an inferior species to rationalize keeping them as slaves.