Sarah Gailey is the author of two novellas, River of Teeth and Taste of Marrow, about an alternate America that domesticated hippos, which promptly ran swam feral in the Mississippi. In this Tor.com post, she describes how there wasn’t supposed to be an accompanying map, but one got made anyway.

It had never occurred to me to draw a map. I had written a story that wasn’t an epic, high-fantasy journey across nations. Why would I draw a map? Maps are for bigger stories, right? How does one go about drawing a map? I stayed up that night googling cartography. My search was not fruitful. I tucked that particular insecurity into the part of my brain where I catalogue all my shortcomings as a writer, and I did my best to forget about it.

Imagine, then, my abject horror when my River of Teeth editor, Justin Landon, sent me the following message: “oh hey, btw, do you have a rough map you’ve done for RoT?”

I said no, and he asked me to put something together. I hedged heavily, hoping that if I said “I will probably do a bad job” enough times, my editor might say “oh, ha ha, just kidding, I would never make you do something this hard! Please, go enjoy a cocktail.”

Reader, he made me do a map. I gritted my teeth, grabbed a piece of paper and an existing map of Louisiana, and braced myself for despair. You’ll never believe what happened next.

I had so much fun.