US didn’t have many large prosperous cities in the west or most of the south until very recently. Railroads and AC really changed where people lived in America.
I was going back to 1940 as recent history, back in say 1840 the largest southern city was New Orleans followed by Charleston, SC at 29k people and Louisville, KY at 21k.
To wonder where the wealth went you need to look at places that where at some point wealthy. Wealth however takes time to accumulate because waves of immigrants or kids from population booms don’t tend to have a lot of wealth.
https://1940census.com/Img/1940_census_map_usa.jpg vs zoom in a little here: https://maps.geo.census.gov/ddmv/map.html
LA and New Orleans should have made the list, after that it’s more questionable.