I've read a number of articles describing Detroit's decline into chaos, and if I recall, the beginning of the end started when they city started throwing money and promises at minority communities to address their lack of opportunities and high unemployment. To pay for these programs, the city started raising taxes on businesses. After the riots of '68, they made more promises, and increased spending. Tax increases soon followed, as the population began to recede.
Rather than spend money on improvements and to keep Detroit viable and interesting, they threw it into a dark hole of socials services payouts, and public employee pay and benefits. Eventually, most major businesses started to move out of the city to less costly surrounding cities, abandoning the inner city. From that, the die was cast. The tax base disappeared, people moved out, and what was once home to some of the most highly paid citizens in the country has turned into a set piece for Armageddon II.
Baltimore, and many cities across the country are poised to make the same mistakes. Rather than encouraging business and opportunity, the liberals running these cities will turn to payouts to buy votes from the "needy", and set in motion the same result. Downtown Los Angeles has teetered on this cliff for decades.