So, I did a brief study of the poorest 10 cities over the past 30 years. For the record, these cities all had over 50% minority (Black, Latino) populations, so they seem relevant to the thread.
America's 10 Poorest Cities - ABC News 
I looked at which major political party ran those cities for the past 30 years. It takes a bit of legwork, but you can trace a city here 
The Political Graveyard and then look up the mayor/counsel members on that site as well as several places, including wikipedia. 
Then I looked at which major political party ran those states for the past 30-35 years. 
Results: In the cases of the cities which I traced, Democrat councils and mayors ran those towns for 80% or longer over the past 30-35 years. In some cases, it was impossible to find party affiliation, so I left that leader out. Below is a listing of the cities, their current mayor's party, and the % of time they've had a Democrat for Governor over the last 35 years.
Please forgive the formatting.  It looks correct in edit mode, but won't render with the correct spacing on the page.
City                      Current Mayor      % Time Democrat Gov 
Pine Bluff, Ark.         Democrat            66%
Albany, Ga              Democrat            80%
Macon, Ga.             Democrat            80 %
Rocky Mount, N.C.   Democrat             80%
McAllen, Tx             Democrat            20%
Brownsville, Tx        Democrat             20%
El Centro, Calif.       Democrat             30%
Yuma, Ariz              Republican           61%
Saginaw, Mich.        Democrat            43%
Flint, Mich               Democrat            43%
Hopefully, my facts will not be proven erroneous.
There have been opinions made by members that, what are traditionally Republican policies are responsible for the disparity of wealth. However, this sampling seems to indicate that, at best, the leadership was shared. At worst, it was actually 30 years of Democrat policy which has produced the 10 poorest cities. 
Feel free to correct my facts or suggest why they may not be relevant.  I would appreciate a level of civility in discussing this.