You can see how the photographs inspired Towles to write a novel, more than a decade later. He says on his website that the book began with the idea of someone attending the opening of Evans's New York exhibition - which didn't happen until the 1960s - and recognising a figure on the wall who had gone through a transformation.
The attendee became Katey Kontent, the heroine of the novel, and the portrait became that of her one-time love, socialite Tinker Grey.
Towles writes on his website: "One of the reasons the Evans portraits stayed with me all those years is that they are fundamentally haunting - and, in part, I think this is because they manifest the public/private paradox of the subway ride.
"On the one hand, these commuters are in the most public of environments - a crowded subway car in the largest, most racially diverse city in the world. But on the other hand, the anonymity secured by this chance gathering of strangers, by the relative brevity of the ride, and by that start-of-day/end-of-day weariness, all seem to prompt the riders (or allow them) to drop their guard.
"We, as viewers, thus get a glimpse not simply of social class and ethnicity, but of the individual histories, sentiments, and dreams, that lie just beneath the surface."
We're trying to pin down Amor Towles for a Q&A next week, so we might find out more about his inspiration. I'm about a third of the way through the book and becoming more engrossed in his recreation of 1930s New York with each page I turn. I'll keep you posted.
Check in with us on Friday for a Q&A with Rachel Simon, author of Christine's September feature read, The Story of Beautiful Girl.
Thanks for all your entries in our competition this month. We'll share some of your carefully considered answers in the next few weeks. Congratulations to Alan Wheatley, Kate Duggan and Sandra Haigh, who each win a copy of The Story of Beautiful Girl.