NYC becomes the American Montreal (i.e. #2)

[King of Kensington]

Something akin to the Montreal-Toronto shift occurs in the U.S. and the largest city is no longer an eastern port city.   Trying to imagine the scenario (when and why does it happen?)

Between 1870 and 1900, Chicago grew by 500% (from 300,000 to 1.7 million).  However after that point Chicago ceased to gain on NYC in population.  So there'd have to be some reason for Chicago to keep growing faster than NYC to surpass it.

More realistically, it's probably the West Coast rival, Los Angeles, in the latter half of the 20th century.  I guess NYC doesn't recover from the financial crisis for some reason.  But it's strange to think of L.A. being #1 given that it is not a major financial center (and it's not as if Chicago was really in a position to lure away New York).

Come to think of it, Toronto displacing Montreal as #1 occurred around the same time L.A. displaced Chicago for the #2 spot in the U.S.

[pikachu]

It’s hard to picture. NYC bounced back from the urban crisis better than any other Northeastern/Midwestern industrial city, so you need a scenario where NYC collapses harder and longer than it did irl. But even if it follows a demographic path similar to Chicago, the gap between NYC and LA is still so large….

Tbh you might need to go back to the antebellum era, not have Philadelphia squander being one of the country’s financial capitals, and New York not seeing the potential of the Erie Canal.

[○∙◄☻¥tπ[╪AV┼cVê└]

The Chinese Exclusion Act is never passed. LA and San Diego run together as one metro area. Millions of refugees from Asia settle in southern California after WW2. An aqueduct runs from the Columbia River. Tijuana is also annexed by the US.

[Storr]

I could imagine metro LA supplanting metro NYC if it developed with more density. Instead most development was single family housing, limiting how much its population could grow. In the 1950s LA considered building a monorail system (more info in the youtube video below), but it never happened. At the same time Toronto was building its Subway, which resulted in denser development.

In my opinion if LA had built a BART or Washington Metro like system in the mid-20th Century it could have realistically reached metro New York's population. Of course, that's assuming New York had a worse late 80s and 90s urban recovery/revitalization.

[Sol]

I have a vagueish alternate history scenario kicking around where the capital gets moved to Chicago, either as a result of Maryland seceding in the Civil War or populists wanting to move it westward. Neither is exactly plausible, but it's hard to come up with anything better.

[Samof94]

Nobody has mentioned the elephant in the room yet, which is that both NYC and Chicago speak English yet Toronto and Montreal speak different languages from each other(English and French respectively).

[Skill and Chance]

The jumping off point would probably have to be in the 19th century.  New Orleans would be the leading candidate.  Probably requires a combination of:


a. Early industrial activities are more sulfate aerosol intensive and less carbon intensive, so the net effect of industrialization on climate is cooling and falling sea levels relative to early 1800's conditions

And:

b. earlier and stronger Catholic activism against slavery, potentially leading to abolition at the state level pre-Civil War, or at least leading to a strong enough anti-slavery minority that they stick with the Union in the Civil War like the Border States.  In fact, Union control of the mouth of the Mississippi from day 1 might preempt the Civil War entirely or turn it into something like the Whiskey Rebellion that is easily put down in a few weeks.  A free New Orleans could conceivably overtake NYC in the late 19th century.

Or, failing that:

c. Longstreet's forces resoundingly defeat the white supremacist militias in the 1870's.  Perhaps he becomes governor.  An aggressive response to the Redeemers continues and most Reconstruction-era policies are never repealed at the state level in Louisiana, even as they collapse in other states.  New Orleans absorbs much of the Southern black population in an early Great Migration, and much of the open-minded Southern white population with it.  Decades of substantially free elections make it the least corrupt and most attractive place in the South to do business, so it absorbs the early 20th century oil and gas industry and becomes a stronger and stronger trading hub.  NOLA eventually overtakes NYC during the Great Depression.