Nell Irvin Painter is an African-American historian at Princeton. I just finished her fascinating History of White People. The big story is what a slippery category "White" is, and how many today considered "White" used not to be. My German and Scots-Irish ancestors, some of whom probably arrived as indentured servants (i.e. temporary slaves), were called "guano" (birdsh*t) by Ralph Waldo Emerson in 1851. Emerson of course placed Anglo-Saxon English at the top of the racial hierarchy.
Irish Catholics in turn were moved up into whiteness when the "swarthy" southern Europeans and eastern European Jews arrived in the late 19th century and early 20th century. These latter would become "white" in the 20th century, but not before racist hysteria slammed the American immigration door shut just before Jews and others desperately needed to escape from fascism in Europe.
Painter ranges far and wide, detailing efforts to define the poor as a separate race, and poverty a hereditable condition. Not to mention nonsense about skull measurements, and mythical histories of mythical peoples like Saxons, Nordics, and Aryans, all in a desperate attempt to have a bright line between White and non-White.
Now we know that no such line exists, but not before "race experts" spent a couple generations in power in the academic establishment. Good cautionary tale for being careful and modest when we attempt to talk about ethnicity and development today.