A paper that Alice Willard and I wrote for the 1993 International
Studies Association meetings is now available over the web. The title is
"Systems of Cities and World-Systems: Settlement Size Hierarchies and
Cycles of Political Centralization, 2000 BC-1988 AD"
the address is:
http://www.jhu.edu:80/~soc/pcid/papers/17/pcidpap17.htm
The paper is linked to a dataset that contains city population sizes
over the past 4000 years.
chris