Last week I commented on nicknames for cities. Pondering this deep subject further, I conclude that we naturally apply the linguistic rule of ambiguity to city nicknames.
If the second word is City:
You CAN leave off the City when the first word is unique. Ponca, Dodge, Cawker.
When the first word is ambiguous, such as a state or a generic word, you CAN’T leave off the City. Kansas City, Oklahoma City, Arkansas City, Junction City, Strong City.
You can abbreviate the name in various ways.
KC for the metro area, KCK and KCMO for the Kansas and Missouri sides. In this case omitting City would be especially tricky. You’d have Kansas, Kansas and Kansas, Missouri.
OKC for Oklahoma City, no further disambiguation needed.
Ark City for Arkansas City, and (informally) Junktown for Junction City.
Polistra's Mill 