Central to the plot of Mumbo Jumbo is the 'virus' that is Jes Grew, a cultural phenomenon that is spreading across the United States is believed by the Wallflower Order to be disintegrating the root of Western Culture. As it is described in the first couple pages of the book, "We knew that something was Jes Grewing just like the 1890s flair-up. We thought that the local infestation area was Place Congo so we put our antipathetic substances to work on it, to try to drive it out; but it started to play hide and seek with us, a case occurring in 1 neighborhood and picking up in another. It began to leapfrog around us." (4) Although Jes Grew is a fictional phenomenon (or at least that's what that Atonists say), the features and patterns of Jes Grew mirror those of the spread of jazz during the Jazz Age.
The Jazz Age was a period in the 1920s and 1930s during which the style of jazz music and everything that accompanied it spread and got its footing in American culture. Not so coincidentally, Mumbo Jumbo is also set in the 1920s (well, most of it is) and the spread of Jes Grew seems to have peaked around this time. Originating in New Orleans, jazz spread up North and around the country as African Americans moved out of the South during the Great Migration. As African Americans moved North for job opportunities and to escape the oppressive system of Southern sharecropping, they brought jazz with them. The path jazz took is similar to that of Jes Grew. Jes Grew is said to have originated in Congo Square (a spot that has also had a tremendous influence on jazz) in New Orleans and spread all over the country. Mumbo Jumbo itself is set in New York, which was also a prominent center for jazz and Jazz Age culture, especially Harlem.
