City-creation is a thing of mine... I'm a former seasoned Caesar player!
Not strictly a city, more a town, but still, here in the United Kingdom using an example near me:
Looking at some point during 1974 or the 1990s as a POD:
In OTL, Wigan moved from Lancashire and into Greater Manchester from 1 April 1974 to form the Metropolitan Borough of Wigan (or as the road signs refer to it, "Welcome to Wigan Borough", with the passing of the Local Government Act 1972 on 26 October 1972.
Bolton also moved from Lancashire, creating the Metropolitan Borough of Bolton.
Bury moved from Lancashire into Greater Manchester, creating the Metropolitan Borough of Bury.
WI, in an ATL, Wigan and Bolton formed one larger metropolitan borough, perhaps in the 1990s or late 2000s, replacing both separate boroughs with one merged one?
Or alternately, in the ATL, Wigan, Bolton and Bury merged into one cohesive borough (not sure what to name it, "Wigbolbury" ?? Metropolitan Borough of Wigan, Bolton & Bury ??)
What effect could this have on local politics? (not that I understand much about that, but also day-to-day stuff would be impacted, NHS services, policing etc. ?)
In the U.S. what size town would these towns be equivalent to?