The St Paul office of Montgomery Ward where my grandma worked was known as the “Northwest office.” I’m not sure of the exact boundaries of their service area. The origin of only a few letters has been preserved. Those letters came from Minnesota, Wisconsin, South Dakota, North Dakota, Montana and California. However a few of them seem to have been credited to the wrong state.
I’ve put those places together in this post. I have some ideas of what the mistake may have been and have included that in the “Possible Alternate” spaces. I’ll be updating as I find out more and hopefully nail down the correct locations.