While there's no question that Chicago's city proper population has gone down much of the alleged migration has been either overblown or just flat out incorrect. See this story about the serious undercount -- by 250,000 -- in the 2020 census.
https://www.nbcchicago.com/new...
From person experience and what I've read there's two large groups leaving. Older, retired folks who are moving to Florida or just over the border in Wisconsin or Indiana looking for lower taxes. There's folks who've gone from paying $30,000 a year in property taxes in the suburbs to paying $5-7,000 in Indiana or North Carolina.
But those houses are not going away and are not sitting empty and those folks aren't renting apartments in the City. Also, City of Chicago employees have to live in the City during their jobs but as soon as they retire they move to Indiana or the burbs. Often Indiana or elsewhere for the lower property taxes.
And there's been a well reported migration of African Americans from the south and west sides to northwest Indiana.
And it's hard to blame them when you see what $300,000 buys you just over the border: A 3 bedroom, 2 bath house with decent schools and NO crime whatsoever. I've seen towns where a couple of kids shoplifting liquor from the local liquor store is the big crime of the weekend.
Anyway, I know I read that you're supposed to invest in growing cities but I also know that almost every kid who graduates from a Big 10 school wants to move to Chicago and work. So we're constantly getting an influx of immigrants and people at the bottom of economy and the much higher up folks.