Okay here is a better question. Why is income inequality worse in cities ran by Democrats?
Well most large cities lean democrat and are obviously more likely to elect democratic leadership, so essentially almost all large cities are run by democrats.
Atlanta and Detroit are both large democratic cities that are predominantly African American. Yet Atlanta has been on the upswing while Detroit has been in decline.
So, labeling city success primarily on political ideology would not be accurate due to the fact that many of these cities have similar political ideology, yet are in completely different situations.
In terms of income inequality, I'll use Atlanta as an example. There are parts of Atlanta that holds the richest individuals in all of the south, and there are parts that are filled with poverty.
Now the question is, why is there this type of income inequality in one city? Well my theory is that the inequality is due to the fact that large cities are clearly more likely to hold populations of different socioeconomic classes due to the sheer population of the city.
Now, there are many parts of Georgia that are exclusively poor. A lot of these areas are small towns that are predominantly African American and liberal, or predominantly Caucasian and conservative. Regardless of race or political affiliation, there are many towns across Georgia that are below the national average in terms of wealth.
Now directly north of Atlanta, there are suburbs that people would consider exclusively wealthy. The wealth of these suburbs aren't nessesarily a product of excellent government management, but more of a product of affluent families congregating into a single city to raise land value and ensure that their children are in a safe neighborhood with excellent schools.
This leads me to believe that the income inequality in Atlanta and other cities is not strictly due to political policies, but more likely due to simply the fact that the city is quite large, and can contain more than 1 socioeconomic class.