u/theoneandonlythomas

Imagine an alternative scenario where the Chicago Metro was even larger than it is today (roughly 9 - 10 million people) and is say 18 million people. In this scenario the city proper and inner ring suburbs continue growing. The city proper resembles NYC and the inner ring suburbs resemble New Jersey. In this scenario though NYC would also be larger, 30 million metro area with with 13 million in the city proper. Chicago would have maintained and expanded both its interurbans and streetcars, and converted higher demand routes to Heavy Rail and larger metro rail system would be built. Plus more commuter routes would be maintained and electrified like the train to Valparaiso.

I believe such a scenario could have come about had immigration not been restricted from 1870s to 1920s. In this scenario more Europeans such as Jews, Poles, and Italians etc move to the US and there is less internal migration of Black Americans northward. One major driver of the great migration was labor shortages. With more constant inflows of new people and no white flight, European immigrants maintain old world behaviors and family structure longer. Without the Chinese Exclusion act, 1917 immigration act Emergency Quota Act, and 1924 immigration act we would probably have an additional 50 million Americans conservatively. Immigration would have declined eventually because of the great depression, but we would have more of them and they would be less assimilated, so higher fertility rates too.

Chicago would be a city of roughly 6.5 million people in a land area of 228 square miles, though it would possibly be larger in land area too and have annexed more suburbs. But assuming the land same boundaries and 6.5 million people you get roughly 28,000 people per square mile, which is still less dense than Brooklyn.

Inner Ring Illinois Illinois Suburbs Have 1.7 Million addition people

Berwyn - 200,000/3.9 - additional 150,000 - 50,000 people per square mile

Cicero - 300,000/5.9 - additional 220,000 - 50,000 people per square mile

Oak Park - 235,000/4.7 - additional 220,000 - 50,000 people per square mile

Evanston - 390,000/7.8 - additional 310,000 - 50,000 people per square mile

Skokie - 500,000/10 - additional 430,000 - 50,000 people per square mile

Oak Lawn - 425,000/8.5 - additional 370,000 - 50,000 people per square mile

Forrest Park - 120,000/2.4 - additional 100,000 - 50,000 people per square mile

50,000 people per square mile sounds like a lot, but it's comparable to Hoboken and other Northern NJ suburbs.

Outer Ring Illinois has an additional 1.1 million people (there's probably some I am not including).

Winnetka - 90,000/3.8 - additional 80,000 - 23,000 people per square mile

Waukegan 300,000/25 - additional 210,000 - 12,000 people per square mile

Wilmettete - 90,000/5.4 - additional 62,000 - 16,000 people per square mile

Schaumburg - 300,000/19 - additional 210,000 - 15,000 people per square mile

Naperville - 500,000/39 - Additional 350,000 - 13,000 people per square mile

Elgin - 400,000/38 - additional 290,000 - 11,000 people per square mile

Most of these would be about as dense as Newark, NJ at its peek of population.

Northwest Indiana adds 1.9 Million people

Gary - 600,000/50 - additional 540,000 - 12,000 people per square mile

Hammond - 330,000/22 - additional 260,000 - 15,000 people square mile

Munster - 300,000/7.5 - Additional 280,000 - 40,000 people per square mile

Michigan City - 300,000/20 - additional 270,000 - 15,000 people per square mile

Valparaiso - 200,000/16 - additional 170,000 - 12,500 people per square mile

Portage - 275,000/25 - additional 225,000 - 11,000 people per square mile

Chesterton - 100,000/9.4 - additional 90,000 - 11,000 people per square mile

La Porte - 100,000/12 - additional 80,000 - 8,000 people per square mile

Gary Indiana would become like Newark NJ did before it collapse and be cultural hub and city in its own right and Northwest Indiana as a whole would resemble New Jersey.

About 100,000 people give or take are added to Michigan towns with Interurban connections to Chicago. These towns would serve a role similar to connecticut.

Benton Harbor - 60,000/4.4 - additional 50,000 - 15,000 people per square mile

St Joseph - 50,000/3.2 - additional 40,000 - 15,000 people per square mile

The Suburbs would have roughly 4.7 million additional people and the city itself 3.9 million additional people, give you a metro area with 17 - 18 million people, comparable to NYC today. The Chicago region has a GDP per capita 80,000 per person vs 100,000 for NYC. In this scenario Chicago would have 100,000 per person and NYC would be about 120,000. Chicago's economy would about 1.8 trillion in value vs 700 - 800 billion today and NYC would be about 3.6 trillion vs 2 trillion.

The data is few years out of date, but what I could find.

https://en.wikipedia.org/wiki/List_of_U.S._metropolitan_areas_by_GDP_per_capita