How do you designate fortress cities/commercial districts?

[pyremind]

I have lots of big cities but don't see where I can declare them.

[Sauske]

First of all, depending on landmarks or other factors that make said province more useful for recruitment or economy, respectively.

If that doesn't matter (no meaningful landmarks available, both provinces are the same size etc.), then I just look at the geography of it - where would recruitment be more convenient? Usually closer to the front. Also, not much point having two designated mustering provinces right next to each other.

[Garatgh Deloi]

Its part of the "Matters of State" mechanic that Yuan Bo's faction (the jade court) has.
https://steamcommunity.com/sharedfiles/filedetails/?id=3168285219 https://steamcommunity.com/sharedfiles/filedetails/?id=3168285769

[pyremind]

Ah thanks