Where did white Americans come from?

The only book I can think of that so thoroughly and elegantly deconstructed what I thought I knew as Nell Irwin Painter's The History of White People is Edward Said's Orientalism. Just as I would feel completely inadequate to describe how Said's textured and wise work of literary criticism made its argument, so I feel utterly unable to summarize what Painter has done in her 2010 cultural history.

Fortunately I don't feel I have to, as she summarized her themes in a New York Times oped written in response to the Charleston massacre at Emanuel African Methodist Episcopal Church.

We don’t know the history of whiteness, and therefore are ignorant of the many ways it has changed over the years. If you investigate that history, you’ll see that white identity has been no more stable than black identity. While we recognize the evolution of “negro” to “colored” to “Negro” to “Afro-American” to “African-American,” we draw a blank when it comes to whiteness. To the contrary, whiteness has a history of multiplicity.

... In the mid- to late-19th century, the existence of several white races was widely assumed: notably, the superior Saxons and the inferior Celts. Each race — and they were called races — had its characteristic racial temperament. “Temperament” has been and still is a crucial facet of racial classification since its 18th-century Linnaean origins. Color has always been only one part of it ....

In the 19th century, the Saxon race was said to be intelligent, energetic, sober, Protestant and beautiful. Celts, in contrast, were said to be stupid, impulsive, drunken, Catholic and ugly.

... By the 1940s anthropologists announced that they had a new classification: white, Asian and black were the only real races. Each was unitary — no sub-races existed within each group. There was one Negroid race, one Mongoloid race, one Caucasoid race. Everyone considered white was the same as everyone else considered white. No Saxons. No Celts. No Southern Italians. No Eastern European Hebrews. This classification — however tattered — lives on, with mild alterations, even today.

For a glimpse of Ms. Painter's thought, read the oped or, much better, the book.***Of particular interest to me in Painter's History was her short, but acerbic, description of the contributions to racial nativism in the 1920s of the Saturday Evening Post writer and historical novelist Kenneth Roberts. Roberts was some sort of collateral relative of my family; I was raised to applaud his portrayal of American revolutionary war events and people, though I don't think I ever ready any of his novels. Apparently he was one of the leading popular promoters of immigration restrictions (which were passed in 1924) on "hereditarian" grounds. Why, if the pure, "white" United States let those southern Europeans and Catholics and Jews come in to do factory work, they would breed with us! This would become a mongrel society! My older relatives had some of these "hereditarian" prejudices, though they were moderated by having lived through the war against Nazism.***After reading Painter's History I asked around, not very exhaustively, among my academic friends: is this book being taught to college students? Apparently not, or not much. This is unfortunate. The book should be canonical, an element in the knowledge base of educated people. I wonder, is Orientalism canonical?