Computational Limits of Empire

The tabulation of the 1880 US census took 8 years to complete. As preparation began for the 1890 census, it was estimated that tabulation would not be complete until after the 1900 census began! The computational load was declared to be too great; an alternative approach was needed.

The problem was solved by a mechanical computer based on punch cards. A company was founded specifically to build the contraption; that company would later become IBM.

I was thinking about this story, and I wondered: just how large was the US population in 1890? Did other nations reach that population level before? How did they handle the problem?

The 1890 US census counted 63M people, in total (source). How large did the Roman empire grow? Well, the Roman empire seems to have reached its peak around… 60M people. At this point I really started to get suspicious, and looked up population statistics for the ancient Persian empire and the Chinese empires. 50M people for the Achaemenid empire (Persian). China had 30-85M under the Han dynasty, stabilized around 50M for a few centuries, then grew from 45 to 80M under the Tang dynasty.

Next, I pulled up wikipedia’s list of largest empires and Business Insider’s list of top 10 greatest empires. I had to google around for population stats, many of which were not immediately available, but here are the big ones, excluding empires from 1700 or later:

• Rome, 60M (https://en.wikipedia.org/wiki/Demography_of_the_Roman_Empire)
• China, 30-85M (Han), 50M, 45-80M (Tang) (https://en.wikipedia.org/wiki/Demographics_of_China)
• Abbassid caliphate, 50M (https://simple.wikipedia.org/wiki/Abbasid_Caliphate)
• Umayyad caliphate, 62M (https://en.wikipedia.org/wiki/Umayyad_Caliphate)
• Achaemenid (a.k.a. Persian), 50M (https://en.wikipedia.org/wiki/List_of_largest_empires#Largest_empires_by_percentage_of_global_population)
• Yuan dynasty, 60M (http://www.businessinsider.com/the-10-greatest-empires-in-history-2011-9/)
• Spanish empire, 68M (http://www.businessinsider.com/the-10-greatest-empires-in-history-2011-9/)
• Mongols, 110M, one generation only (1270-1309) (http://www.businessinsider.com/the-10-greatest-empires-in-history-2011-9/)
• Mauryan Empire, 50M (http://www.newworldencyclopedia.org/entry/Maurya_Empire)
• Seleucid, 30M (https://en.wikipedia.org/wiki/Classical_demography)

There were a number of smaller “empires”, mainly the predecessors and/or successors of empires on this list. But on the other end, only the Mongols managed to scrape together an empire of over 100k people, and that empire split within a generation (spinning off the 60M-person Yuan dynasty).

Yes, this is a far cry from systematic. Yes, there’s room to complain about selection. Nonetheless, there is at least a very noticeable tendency for pre-modern empires to max out in the 50-70M population range.

Is the empire population cap due to computational limits in governance? I’m not sure how to properly test that hypothesis, but it does seem awfully suspicious that the founding event of the modern computing industry was triggered specifically by the US passing that 60M population mark.

One interesting question to pursue next: how did other modern nations/empires handle passing the 60M population mark? India and China both achieved sustained growth and built stable nations of over 100M people during the early modern era. Presumably the British empire’s population was also beyond 100M during much of the 19th century. Did these states also face computational blockades? What techniques did they introduce which might explain their ability to overcome the 60M person cap?