I am not sure that our view of territory matches that of the supernatural races. Case in point. The Red court territory was Central and South America. Yet they had operations in North America, Africa, Europe which they used in their war with the White Council. It was also noted that wizards of the White Council lived in Central and South America despite the Red's control of that space. (examples given in books)
I am guessing that territory is more of a measure of effective dominance than exclusive use. The Reds controlled Central and South America and thus dominated the local governments, had a strong presence in most countries, and were clearly the most powerful supernatural nation in the area. Anybody who lived in this region had to respect Red Court power and live to some extent with their dictates. This is why Bianca had to respect Harry in Chicago - she was operating in .White Council territory. Harry's ability to threaten her would have been much less if the same conversation occurred in Bogota
I suspect there are many pockets of supernatural races in Central and South America. Any one pocket might be relatively weak in the grand scheme of things, but collectively I suspect there was a lot of power there. Now that the Reds are gone, it is these pockets that have the most opportunity to expand -- and compete against outside powers moving in (like the Formor). Of course, not every supernatural races is expansionistic or able to expand quickly even if so inclined. But I suspect most of them will expand their own territory to some extent now that the Reds are broken.
