"Race" (a concept and social action) appears to have been accepted by "the state" (the repressive and administrative function) in the United States as a self-evident fact in the state's law, regulation and administration.
To what extent was race important in the day to day actions of the state in the United States? Both in discriminating between races, and in asserting that race existed as a human category?
Were there present in the United States common "sciences" of race, or any other clear and shared cultural explanatory systems, of why and how race existed at all and how it worked?
Edit by the OP:
(so that future edits and answers include the following details that made me ask this in the first place)
I like the new form of the question (edited above by @SamuelRussell who has summed up very well what I has asked initially: maybe he will do the same for the text I am adding here), but, although I cannot claim any credit for it anymore, I would like to see answers relating more to what @PieterGeerkens' comment calls the modern era, even to the contemporary one, in relation to reasons/causes of the general use/significance of "racial" terms - and not just in the context where rights are guaranteed free of racial distinctions, but also where such distinctions are strongly made, as it can be seen in the Wikipedia article Race and ethnicity in the United States Census . As a non-American that never lived in the US I am fascinated (with "mixed feelings" that I want to un-mix) by the fact that racial distinctions are taken for granted. For example, I read that
Race and ethnicity in the United States Census, defined by the federal Office of Management and Budget (OMB) and the United States Census Bureau, are self-identification data items in which residents choose the race or races with which they most closely identify...
The data are self-identificatory, but people are offered a choice in racial terms. How is that historically possible? How was that arrived at and how is it perpetuated?
Wikipedia articles give a lot of details about such terms but the details can be confusing.
The United States Supreme Court unanimously held that "race" is not limited to Census designations on the "race question" but extends to all ethnicities, and thus can include Jewish and Arab as well as Polish or Italian or Irish, etc. In fact, the Census asks an "Ancestry Question" which covers the broader notion of ethnicity initially in the 2000 Census long form and now in the American Community Survey.
"Origin" can be viewed as the ancestry, nationality group, lineage, or country of birth of the person or the person's parents or ancestors before their arrival in the United States. People who identify as Spanish, Hispanic or Latino may be of any race
But what is the race then? If I learn Spanish, move to Spain and then to US - while I'm of Romanian "ancestry" (meaning nothing else that I'm born in Romania, I also have that citizenship and speak the language) now living in France - can I declare myself there as Latino or Hispanic, given that (like many other people of many other "ancestry" - European, Turkish, Arab or Jewish) I even "look like one"? "Looking Hispanic" doesn't mean anything, I know: I could have been born in Romania from an African father or mother (students of many origins in Bucharest), or from a Tartar one (old minority close to the Black Sea), and I would have looked "African" or "Asian". But if "looks don't matter", what is the justification of even using a term of "Black" or "White" as a race? Is it just the "ancestry"? How can that be proved? It's just a cultural declarative self-identification?
It may well be that "race" is determined by a specific need to use the word (a Wittgensteinian definition of a word's meaning): is the necessity to use such terms political or scientific? Is it the practical necessity (which one?) that upholds the concepts or are the concepts so important in themselves as to structure the discourse?
This is rather complex and confusing, as conventional-linguistic use is dictated by political decision too, so that words can take a different meaning outside American English - for example the European Union cuts it short (Wikipedia article Race):
According to European Council:
The European Union rejects theories which attempt to determine the existence of separate human races.
— Directive 2000/43/EC
So, how can one talk of something that simply isn't there? Why are "ancestry questions" required? Is the diversity of terminology triggered by the diversity of American institutions (with different goals), and is all this helping the perpetuation of such terms (that have a historical "racist" origin doubled by outdated/dubious scientific taxonomy).
The problem with the Wikipedia articles is that they also take for granted terms that I find at least partially meaningless.
For example, a simple phrase like
The United States is a racially diverse country. The growth of the Hispanic population through immigration and high birth rates is noted as a partial factor for the US' population gains in the last quarter-century. The 2000 census revealed that Native Americans had reached their highest documented population
In order to even say that the country is racially "diverse" one has to already judge racially upon the people. The growth of the "Hispanic" population is calculable because people are oriented to declare themself as such or have been simply put in that category by the authorities. As for the "Native American", is that also a choice? CAn one chose not to be Native American? Can one be acknowledged as such based on its own free will? - And after all: what has all this to do with "race"?
I am not expecting answers to all these sub-questions, only that an answer takes into account the perspective defined by these.
It may well be that my edit will impose the closing of this question, but at least I have made clear the context of the question. Feel free to edit/shorten it, but try to tackle the main aspects that I have tried to put forward.