A person who is especially proud to be from a particular city, and puts down others from opposing cities. They rep their city as if it's a sports team. This is especially true in the US.
Could you please suggest a single word one could use to describe such a person well (not a gross hypernym like 'supporter')?
Booster does fall into the hypernym category, but it collocates with cities and municipalities. If you don't find a single word, perhaps city-booster.
booster (n.)
One that boosts: such as an enthusiastic supporter
M-W
US
A person who enthusiastically supports or promotes something (= tells people how good it is):I don't want to come across as a booster for any particular product.
The mayor and town boosters hope the new ballpark will be a catalyst for development. Cambridge
A booster is someone who supports a sports team, organization, person, or place very enthusiastically.
Collins
In the local newspaper, the Corona Daily Independent, city boosters boasted that great golf tournaments held at the Parkridge would accrue national and international recognition for their citrus belt community and generate publicity benefits that would attract tourists.
Alison Jefferson; Living the California Dream (2020)
On the general brokers side, the typical realtor was an enthusiastic booster of urban planning and land-use regulation, mostly beginning around 1914 and particularly during the early 1020s.
Marc Weiss; The Rise of the Community Builders (2002)
The River and Harbor Convention was a classic city-boosting event. Chicago boosters inserted into the convention's printed proceedings a twenty-page statistical appendix that celebrated the city's development. ... The city's boosters had lobbied strenuously to convince eastern organizers to choose Chicago for the convention site.
Robin Einhorn; Property Rules: Political Economy in Chicago, 1833-1872 (1991)
