If dems get control of all three branches of government, would they rule it like they have ruled LA, SF, CHI, DT, BALT, PHLI and NY?

You are exactly right

America would be lucky if it turned into country like many of those places. Of course, Detroit is a notable problem City but that's not because of democratic rule but because of deindustrialization. I know that it's not because of democratic rule because other similarly Democratic cities, including New York and Los Angeles, are thriving. New York, Los Angeles, and San Francisco, are some of the wealthiest cities in the world. Their economy is almost infinitely better than the economy of many of the impoverished states which Republicans have ruled for decades such as Mississippi, Alabama, Arkansas, and Idaho. If the American economy overall became like the economy of California or New York it would be a fantastic Improvement for the lives of many Americans

Only in regressive fantasies.

Clearly you live out in the middle of nowhere in a trailer and you are frightened all the time. I feel sorry for you.

Probably................

Of course. We'd have high taxation, bankruptcy, and equality (everyone equally miserable).