There’s the movie, the book, and then there’s the local backstory: For 30 years, Victor Green helped travelers navigate their way through a segregated America—including a segregated Los Angeles. Top image: Viggo Mortensen (as Frank “Tony Lip” Vallelonga) and Mahershala Ali (as “Doc” Don Shirley) riding in a 1962 Cadillac Sedan DeVille, from the 2018...