One measure I’ve used to determine changes in wealth for a given geography is equalized assessed values (EAV) from counties. Counties generally determine EAV for property tax purposes and they usually organize it by local municipalities. It gives a strong indication of the amount of wealth within a community.
A story done by the Detroit Free Press in 2013, when the city in the middle of its bankruptcy filing, found that Detroit’s EAV peaked in 1958, equal to $45.2 billion in 2013 dollars, and dropped by 2/3 to $15 billion by 1980. It bottomed out at $9.6 billion by 1996, got a housing bubble rebound to $16 billion by 2006, and fell sharply again until the bankruptcy. Link: