I'm really on the fence about assigning places or dates/events a sign. When it comes to events (such as wars), I think you'd have to look at the natal + transits for the leaders involved. Lots of complexity.
Similarly, I think a city or a town can't have a sign. I think a city or a town's vibe can be dependent on who is running it though. I would look more to the leadership at its beginning. Who was the Mayor? The Sheriff? Council?
That makes more sense to me.
Edit: It doesn't make me right... just saying what makes sense to me.
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“Most people would rather be sheep than stand on their own with antlers on.”