The pattern for many big cities is similar - as the cities became more liberal, the productive people began to migrate outward.
From my experience in Cleveland, OH, several events preceded or coincided with the drop in population. The Hough and Glenville riots in the late 1960s and forced busing in the 1970s come to mind. There’s more, of course, but these 2 stick out in my memory.
Remember that not only the exodus of Middle/Working class white from the urban tax base was disaster but the Inner Cities are full of Non-Profit/Tax Free Hospitals, Churches, Universities and Charities + Gubermint which add little to the tax base. Very soon the Feds will start full scale vouchering of the section 8 housing occupants so they can spread the misery! Wait and watch it happen, the plan will be to gut the 2A and then unleash the Orcs, the Blacks and the Illegals!