Need a drop-down list to adapt to another drop down list (Region/State)
I have a site with classipress in Sweden and it is crucial that users can ad information about were the ad is located. I would like this information to be added with drop-down lists of different regions in Sweden. The problem is that Sweden has quite alot of regions and in every region there are a couple of "states" I don't know if this is the correct translation for the geographical system in Sweden but lets call it regions and states.
So the issue comes when I want to show a list of our "states".
It is not an option to make a drop-down list with all the states in Sweden since there are over 300. So I will need a drop-down list with the regions and for each region the next drop-down list shall only show the results of that region. This is a pretty common function on sites out there but I am wondering over the possibilities to add it to this theme.