The reason I’m asking this is I had a thought.  Could I find a province I don’t want a town in, create a city there, raze it, create a new one, raze it, and repeat to earn expansion stars?

If anyone knows, I’d really like an answer to this, as it feels like an exploit and I don’t think it would be fun if this becomes the meta.

Hmm... never tried that in Lucy OpenDev, but I doubt it would work this way. For the exploit to function, conditions which fulfill Expansionists Era Stars must, once it is achieved, remain permanent. However, even in-game benefits of cultural Wonders (e.g. the Great Light House of Alexandria) can be taken away from opponents, if you temporarlly control the City that contain such Wonders. (No full-ownership or diplomatic deals needed) After signing White peace or losing control of the City, those benefits disappear. So I assume it is also the case for Expansionists Era Star.

Or... do you remember how Agrarian Era Star was counted? Did we lose progress when sacrificing Populations to build something else? I can't recall that correctly... If it had counted the current number of total Population in the Civilization, then it would be natural to  assume that Expansionists Era Star only counts the current number of Territories.

Sadly I don't remember how Agrarian stars work either...

I just saw the expansionist star description from a YouTube video, and the language on the tooltip seemed to imply it's based the total number rather then x amount of plus 1's.

I really hope it's based on total.  While winning is always fun, I think doing this would be very boring.

I recall that yes, you did lose agrarian progress if you lost population, so I assume it would be the same with expansion and outposts. Once you got a star, you couldn’t lose it of course, but you’d lose progress for the next star either way.

Thanks for letting me know about Agrarian stars.  Next time I get a chance to play the game, this is the first thing I want to test, because, after thinking about it, I specifically remember not losing era star progress when spending  gold or influence.