What is the importance of Chicago in the novel, The Wrong End of the Telescope?

While the American city does not appear as a location in the present timeline of the story, Mina narrates many anecdotes and flashbacks that take place in Chicago, which is where she still currently lives with her wife Francine. Most of these flashbacks revolve around Mina’s relationship with Francine, but she also tells stories related to Francine’s work in Chicago, as well as friends and loved ones in the area.