Police and the "whitening" of Americans

There is an important, but under-discussed part of police history is that is also the history of the "whitening" of immigrant groups that came to the United States.

In the early 19th century, American cities didn't have police departments. Boston was one of the first. At the same time that Boston was constructing a police department specifically to control the less well off or immigrant areas in town, New England and America in general was receiving an enormous influx of Catholic Irish, fleeing the famine and oppression. Famously, what they met on the white Protestant shores of the New World was, at first, No Irish need apply signs. The Irish were considered sub-English - in England especially, but as well in the U.S. Although Germans were also migrating, on the whole, they were protestant. The combination of religious prejudice plus the aura of prejudice against the Irish in England put them into the class of the "not-quite white".

In the U.S., the rituals of becoming white have been explored for the last twenty years by many scholars. Here's an overview of the field.

What interests me is the way police work acted as a vector into whiteness, partly because police work allowed for the direct targeting of black subjects. To become white in the white settler state, a common strategy was to distance oneself from, and stigmatize, black people.
I'm not aware of any borrowing in this field from Rene Girard's theory of negative mimesis. In simple terms, Girard hypothesizes that the social order is built around a fundamental violence: the targeting and expulsion of a scapegoat. In order to not be the scapegoat, one engages in negative mimeses - trying to become the scapegoat's Other.

I have many criticisms of Girard's total explanation of the social order, but the scapegoating and negative mimesis process does work well with the becoming-white of various ethnic groups - the Irish and the Italian-Americans in particular - and the way that policing played a symbolically central role. One that carries over today. The police enact the neurosis of whiteness, to put it in sharp and exaggerated terms.