With his wife’s help, Terence Conley walked slowly toward a piano on a recent Thursday at the Jazz Foundation of America headquarters in Manhattan. “Play something nice,” Judith Conley told her husband as she eased him onto a piano stool. Mr. Conley, 51, steadied his fingers above the keys, smiled across the room in the direction of …

The musical Prince of New Orleans has been touring New York in vagabond shoes. “I’ve been walking around at night looking at all the clubs and the restaurants, just trying to figure out a new beginning for myself,” said Davell Crawford, 32, sitting on a piano bench recently at Roth’s Westside Steakhouse on the Upper …

In 1918, the New Orleans Times-Picayune declared jazz “an atrocity in polite society,” and fulminated that “we should make it a point of civic honor to suppress it. Its musical value is nil, and its possibilities of harm are great.” But jazz went on to become an international language, surviving even in dictatorships that banned …