I won't even drive through Camden, NJ (#48) as there are NO safe places. Camden is a garbage dump with bad pollution and no redeeming qualities. I would have put Camden at #2 on the list, with a big gap between #2 and #3.
Ah, Camden, the City Invincible (the city's motto, from a poem by Walt Whitman): .
I DREAM’D in a dream, I saw a city invincible to the attacks of the whole of the rest of the earth;
I dream’d that was the new City of Friends;
Nothing was greater there than the quality of robust love—it led the rest;
It was seen every hour in the actions of the men of that city,
And in all their looks and words.
Most folks these days drive through Camden to get to other places. It is a yawning chasm of poverty, but it has one Fortune 500 company headquartered there (Campbell's), the same number, ironically, as Philly (Comcast). Other big drivers include Cooper medical center and Rutgers satellite campus, but those don't add much to the tax base.
It's not clear to me why Philly is on the list - my city has come alive in recent decades, with a higher percentage of folks living in the core downtown area than anyplace else in America outside of Manhattan. Believe me, this is not like Atlanta where the business center shuts down and is deserted after six. Restaurants and culture abound - there's no better city for craft beer outside of Portland.
So why is it on the list? One strong possibility - the lack of business dynamism. Philly has the hardest time creating jobs because so much of the city's revenue comes from the wage tax. That in turn is the result of the fact that so many of the city's big corporations are non-profits, and don't contribute to the city's coffers through property taxes. Penn, Drexel, Temple, the many teaching hospitals and cultural treasures - these are all beacons that create vibrancy but so little in the way of tax revenues that Philly is forced to rely on the job-crushing wage tax. A number of folks I know live downtown for the culture but work in the suburbs where the jobs are!