What determines city population size?

Harvard economist Ed Glaeser examines the “why” of Zipf’s Law

“ Zipf’s Law ” is one of the great curiosities of urban research. The law claims that the number of people in a city is inversely proportional to the city’s rank among all cities. In other words, the biggest city is about twice the size of the second biggest city, three times the size of the third biggest city, and so forth.

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