Re: Political expansion limits of the Federation
with the possible exception of Earth, which seems to have become the Federation capital in a similar way as Washington DC or Berlin are their nation's capitals without belonging to a single federal state.
Earth does have its own government, it's called United Earth.
We were supposed to see Jaresh-Inyo "federalizing" UE forces in that DS9 two-parter but it got cut for time.
"If the world was perfect, it wouldn't be." - Yogi Berra