"The United States are..." vs. "The United States is..."

This is one of the textbook examples of a place where Big Data can help pinpoint the specific moment in which things changed — Google Ngrams of "The United States are" vs. "The United States is". (And by "textbook example," I mean, "one of the three examples the Google Ngrams people use to prove that their approach might be useful to the humanities, and the one that doesn't just produce a no-duh shrug [like their example where they show that indeed, when the Nazis banned various artists, the frequency of their name-use in German decreased].")

Obviously one should take such data with a grain of salt — it requires good OCRing, good metadata, and careful choosing of proper search query (I used the capital "The" because it seemed less likely to produce problems than a lower-case, e.g. "The bison of the United States are..." — and [indeed, if you use the lower-case, you get a graph skewed to the plural](https://books.google.com/ngrams/graph?content=the+United+States+are%2F(the+United+States+are%2Bthe+United+States+is)%2Cthe+United+States+is%2F(the+United+States+are%2Bthe+United+States+is)&year_start=1800&year_end=2000&corpus=5&smoothing=3&share=&direct_url=t1%3B%2C%28the%20United%20States%20are%20/%20%28the%20United%20States%20are%20%2B%20the%20United%20States%20is%29%29%3B%2Cc0%3B.t1%3B%2C%28the%20United%20States%20is%20/%20%28the%20United%20States%20are%20%2B%20the%20United%20States%20is%29%29%3B%2Cc0)).

While it doesn't change overnight, the trends shown do indicate a fairly rapid change from a period when the plural was more common (1860 and previous) to the point where the singular became most common from the (1900 and beyond).

Of course, understanding why and how this usage changed — the Big Data alone can't show us that. So hooray, historians will not be out of jobs anytime soon, computer scientists' dreams to the contrary.