21 charts that explain how the US is changing by Danielle Kurtzleben: Notes for a lecture, "E Pluribus Unum? What Keeps the United States United"

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We think of our country as a single, unitary nation. That wasn't always the case.

It may not strike us now as odd that we use "The United States" as a singular noun, but this wasn't always the way everyone spoke. Google N-gram data, which tracks words across Google Books, shows that in the mid-1800s, it was roughly as common to refer to the United States in the singular sense as it was to refer to the United States as a plural group of states that were united. It reveals a profound shift in how Americans think. In the late 19th century, Americans appear to have started thinking of the US as one big actor instead of many smaller ones.

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