A few days after the infamous July 13, 1977, New York City blackout, I joined a group of pals setting out from Park Slope, Brooklyn, a neighborhood that hadn’t yet gentrified, for Williamsburg, home to Hasidim and Puerto Ricans in the decades before it, too, became a hipster hot spot. Headed for Jack’s Pastrami King, our favorite restaurant, we were in a jovial mood, though New York was reeling from two days of rioting and looting, which had destroyed 1,600 stores. The riots were another blow to a city still struggling to rebound from its near-bankruptcy of 1975. Jack’s Pastrami...