The Twenty-Seventh City! Man, I have't thought about that book in, jeez, I don't know how long. Close to twenty years, I bet. And yet I remember it reasonably clearly. The main character was the first female Chief of Police in St. Louis -- at the time, the 27th-largest city in the U.S., hence the name -- and she was of some exotic ethnicity, Indian-American I think. (I'm typing this without benefit of an active Internet connection, so this is all off the top of my head.) As I recall, it was fairly heavily promoted at the time of it release, though that may be just because I was living in the Chicago suburbs at the time, and the Midwestern setting made it of particular interest to the local press. I would imagine it's out of print nowadays; I don't remember seeing a copy on the shelves at the store, at least.
Edited: OK, so I've looked it up now, and I guess the reason it got a lot of press was that it was the first novel by someone destined for greater things: Jonathan Franzen, who thirteen years later would win the National Book Award for The Corrections. And it seems I was slightly misremembering the ethnicity of the main character; she was not Indian-American, but just plain Indian, from Bombay. It is in print.
All that aside, I still can't remember if I've read In the Shadow of the Arch. I know I've read and enjoyed a number of short stories by Randisi, and given the Midwestern setting it seems likely that I would have picked this novel up if I'd seen it before. But I think I'm going to have to start reading it to be sure.