I have not personally found that functionality within my Campaign options, but I wonder if you could “sorta” try this by using locations as keywords.

You can target by Marketplace (ie USA/Mexico/Canada) but you aren’t currently able to target by state.

I discussed excluding states/regions with some other sellers at the recent Amazon Seller Summit in Florida and they made a good point about not excluding locations.

I made the case that if I sold coats - I wouldn’t want my ad showing up to someone in Florida because no one wears a coat in Miami - but they made the case that if they had to travel north in the winter time - they are going to be search for coats to buy from Florida.

Overall - we just have to trust that our ads will only be served in relevant searches so geographical location shouldn’t matter as much. I know some want to avoid sales in certain states to avoid sales taxes but at the end of the day I think trying to do that is more hassle than it would be worth.

If your ACOS is high because a search term means two different things in multiple regions (ie soda/pop/coke) then try creating multiple campaigns specifically targeted to regional search terms so they don’t cross each other and drain your budget. Make sense?