When Chicago was first incorporated in 1837, its population was only around 200.

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And according to Wikipedia: "On August 12, 1833, the Town of Chicago was organized with a population of around 200. Within seven years it would grow to a population of over 4,000. On June 15, 1835, the first public land sales commenced with Edmund Dick Taylor as U.S. receiver of public moneys. The City of Chicago was incorporated on Saturday, March 4, 1837 and went on to become the fastest growing city in the world for several decades."