Turning-point years in history

What are the major turning points in history? One way to think about that is to simply look at the most frequent dates used to start or end dissertation periods.* That gives a good sense of the general shape of time.

*For a bit more about how that works, see my post on the years covered by history dissertations: I should note I'm using a better metric now that correctly gets the end year out of text strings like "1848-61."

Here's what that list looks like: the most common year used in dissertation titles. It's extremely spiky--some years are a lot more common than are others.

What years do historians write about?

Here's some inside baseball: the trends in periodization in history dissertations since the beginning of the American historical profession. A few months ago, Rob Townsend, who until recently kept everyone extremely well informed about professional trends at American Historical Association* sent me the list of all dissertation titles in history the American Historical Association knows about from the last 120 years. (It's incomplete in some interesting ways, but that's a topic for another day). It's textual data. But sometimes the most interesting textual data to analyze quantitatively are the numbers that show up. Using a Bookworm database, I just pulled out from the titles the any years mentioned: that lets us what periods of the past historians have been the most interested in, and what sort of periods they've described..

*Townsend is now moving on to the American Academy of Arts and Sciences, where I'm excited to see that he'll manage the Humanities Indicators—my first real programming/data project was putting together the first version of them together with Malcolm Richardson immediately after college.

Numbers between 500 and 2000 are almost always years. You can see here that the vast bulk of historical study has been in the period since 1750: the three spikes out of the landscape correspond to the Civil War and the two world wars. Output decreases in the late 20th century in large part because the data set goes back to about 1850; but as we'll see in the next chart, not entirely.