Gina Mahalek: What was the Manhattan Musical Marketplace that you discuss in your book? David Gilbert: This is a term that I coined to explain the historical formation of New York City as the center of American popular culture at the turn of the twentieth century. I think that many music fans, musicians, and scholars kind of take for granted that NYC has always been America’s capital of popular entertainment, and I wanted to tell the story about how this came to be. Rather than assume Broadway Theater and Tin Pan Alley song publishing just...