A thought experiment considering what would happen if the Chicago Fire of 1871 never happened includes this tidbit about suburban growth:

But then, after that second big fire in 1874, Chicago officials extended the restriction on wooden buildings to cover the whole city.

Elaine Lewinnek, author of the new book The Working Man’s Reward: Chicago’s Early Suburbs and the Roots of American Sprawl, says the aldermen contributed to suburban sprawl by making it cheaper to build outside the city. After they changed the law, a real estate booster reported “a brisk demand for building just outside the city limits.” (Some of those areas outside the city limits in the 1870s later became part of the city through annexations.)…

“Things were already changing, as railroad lines and industry were crowding out housing,” Keating says. “The fire made this happen more quickly but it would have happened anyways. People moved more quickly south to Prairie Avenue or out to new suburban towns like Riverside.”

“The fire pushed 27,000 humble homes out of the central city and the North Side, leading to fewer residences downtown,” Lewinnek says. “Yet suburbanization was already happening before the fire, in elite suburbs like Riverside and more humble suburbs too.”

I have not heard this argument before. At the time of the fire of 1871, suburban populations were very modest. Railroad lines had only been in present in the region for a few decades. For example, the suburb of Naperville, which had just lost out on being the county seat to Wheaton, had just over 1,700 residents in 1870 while Wheaton had 998 residents and Aurora had over 11,000 residents.

As noted by numerous scholars, by the late 1800s fewer areas surrounding Chicago were willing to be annexed into the city (unlike communities like Hyde Park). This is usually attributed to the declining status of city life compared to suburban life alongside the declining price of public infrastructure that made it possible for suburbs to have electricity and their own water supplies. But, the scholars above hint at another factor that would become a long-running feature of suburban life: cheaper housing. If Chicago required less flammable materials for homes, people would move to suburbs that did not have such regulations.

More broadly, it would be worth examining whether major disasters in urban areas push people to move to surrounding areas or even other regions. Do earthquakes in the LA area influence population patterns? How about hurricanes in the southeast? Do people leave population centers after terrorist attacks? It would take some work to separate out the effects of disasters on movement compared to other factors.