Thread by @studentactivism

Lots of people confused by this claim, and with good reason—the data Yglesias used came from a study that estimated population once a century. His chart, and particularly his tweet, doesn't reflect that.

https://twitter.com/mattyglesias/status/1489204666994937868

Here's the source for Yglesias's claim—it's the left hand column. en.wikipedia.org/wiki/List_of_l…

So yes, London was probably the biggest city in the world in 1900, but no, that doesn't mean it was the biggest from 1900 to 2000, or that Tokyo "suddenly" took over that year.

London was apparently the biggest city on earth from the early 1800s to the early 1900s, but it lost that title to New York, not Tokyo.

("What was the biggest city in the world on X date, and how big was it" is a subject I've become fascinated by since I started teaching both halves of world history a decade ago—it's a great way to start thinking about both individual experience and massive historical change.)

(Also, I haven't looked in detail, but I don't think it's accurate to say that all—or nearly all—of the cities on his list were imperial capitals. And of course "empire" is doing a lot of work there—Tokyo is certainly the capital of a global power.)

The below is true, and it's part of why I didn't weigh in on whether Tokyo is biggest now—that's to a large extent a definitional issue. BUT...

https://twitter.com/phyphor/status/1489244303385890818

"What are the actual boundaries of a city" is a much more complicated question now than it was at just about any time in the historical past.

For a long time, for a lot of cities, the answer to "what are its actual boundaries" was "um, the walls?"

But even after that, for a long time—well into the industrial revolution—just about everyone who lived in a city also worked in that city, and vice versa, and most people walked to work. So cities tended to be dense and fairly compact, without a lot of blurriness at the edges.

Trains and buses and subways and cars are one really big reason why it's so complicated to say how big a city is now, and massive regional density is another—in the last while, lots of cities have expanded so much that they only end where another city starts.

So in 2022, "what's the biggest city on he planet?" is in large part a definitional question. For most of human history it was largely an empirical question—the problem in answering it was more gathering and interpreting data than deciding what counts as part of a city.

(Actual historians of old-timey times may feel free to insert additional handwaving into any or all of the above tweets as needed to render them accurate.)

This is not wrong at all. But it's also a good reason to (1) be less gnomic, and (2) not put your gnomic pronouncements in tweets and your actual arguments behind a paywall.

https://twitter.com/mattyglesias/status/1489247341613883398