About Rendering borders

Hi

I'm trying to find a good function for rendering borders for regions. The project is a strategy based game (think risk), have a 3D world with countries that are devided into regions and units that are mounted onto the regions.

So my problem is that I want to make the borders different colors depending on which country owns then (think Civilization).

I have had some ideas, first I tried to devide the different regions into separate object, this was way to expencive since there are a lot of regions. So now I'm trying out an idea where the world could be one object or maybe devided into country chunks.

so about coloring the regions or rather the region borders I first had one idea of using some kind of multitexturing, where one texture only contains the border and color that one though that didn't work out to good. then there was an idea of drawing primitives for the border which I kind of think is just moronic and probably shoulnd't even be tried.

So my question is if anyone have any good ideas on how to do this I'm kind of stuck.