180 years ago today, Chicago—having reached a population of more than 150 white men over the age of 21—was incorporated as a village at a public meeting, population 350. It already had its first priest, who arrived that March; in a few days, it got its first politicians.

17 years later, it was a city of 30,000: 85 times as many people in just nine times the square mileage.

Before photographers wandered the streets, and before the first real census of the country, the city's explosive growth was captured in maps, from the barely-there backwater served by "Rat Castle" to the Columbian Exposition a mere six decades later.