how to get people to join my political forum

[AWS]

Get rid of the redundant forums. Political discussions always turn into debates. Get rid of the political debates category. Move the threads into one of the other forums.

Get rid of all the forums under the general political category. Leave only U.S. Politics and World Politics. No need to have a poll forum. I have one, but, my users prefer to post polls in the topics. My mods will move polls into the poll forum. If they didn't the poll forum would never be used. I have thought about removing it, but, since I have good mods I leave it.

I would also condense the Social Discussions. Consolidate them into one or 2.

Rewrite the forum descriptions if you do any of the above to better define what goes where.

If you leave the forum as is you'll have a hard time retaining new users if they sign up. Less forums makes the ones you have seem more active.
You can always add forums when the need arises. My debate forum started as one category with 2 forums. I've added as needed and since my users requested the forums they are all active.