The cause of death was the glowBULList Free Traitors™ ripped the industrial heart out the USA and gave to Asians, on a silver platter. Now cites are not economically viable and we blame the Democrats? Ludicrous.
GlowBULL Free Trade came to you courtesy of the Democrats.
NAFTA became reality thanks to Bill Clinton. If Bush 41 would have been re-elected the Dems would have dug-in, and it would never have been ratified.
Cities arose because workers needed to be close to work and had little transportation alternatives. That ended in the 50s. Since then, cities survive largely as economic parasites.
The industrial heart of the U.S. would have declined anyway. Once steel declined as a dominant material for manufacturing, cities like Detroit and Cleveland were no longer located in the places where they needed to be to thrive in the next generation of manufacturing in the U.S.