The Bronx's night club scene once rivaled Manhattan's, with more than 200 colorful venues. Jams that defined the hip-hop movement were composed in the borough's school yards. South Bronx bands powered raucous block parties using electricity from street lamps.

Mark Naison sprinkled these facts about the borough's musical heritage—in between his own raps and digressions on street life—on a rambling trolley tour of the South Bronx Saturday, taking 35 passengers on a trip through the area's cultural history. They passed Boston...