WI: No Chicago Fire

The Chicago fire allowed the city to rebuild on a modern grid based system of urban planning, and I think they redid a lot of the layout to make it more conducive to sanitation efforts. Chicago was sort of like the experimental playground of late 19th- early 20th century American architects, so you might not see as much innovation in architectural design. The rebuilding of the city after the fire also made the Columbian Exposition that much more awesome, which is probably a good thing as well.

Nevertheless, I have a feeling that Chicago would've burned down even if the 1871 catastrophe was averted. The pre-fire city was just asking for it, what with all the clustered wooden tenements and all that.
 
It certainly wouldn't be as big. It may still become a transportation hub but it certainly wouldn't be the "Second City"

I think architecture in general might be a little more conservative. A lot of new styles (not to mention the skyscraper) were first tried out in post-fire Chicago because land was cheap.
 
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