Back before Carter was President, he went to the South Bronx. He stood in the wasteland the South Bronx had become, and said he would turn it around.
Four years later, he tried to return to the exact same spot, but no one remembered exactly where it had been. Four years of Carter had turned things around that none of the burnt out landmarks remained. The neighborhood was a middle class residential neighborhood.
trump remembers back when the Bronx was burning 50 years ago, and has no idea that 45 years ago it was turned around.