I've got a E Mail Us page that is showing 9 locations around the sidebar by querying the custom publish type "Marketers." I would like the consumer to have the ability to make use of a drop lower that's populated through the taxonomy "Location." For instance, when the user chooses "California" in the drop lower, it'll instantly update their email list with only individuals posts labeled with California. What's the easiest method to build a storage shed? Also, I do not mind when the page refreshes once the user narrows lower for their Country or Condition.

Ideally, I would like parents groups to become proven in a single drop lower, ie. Germany, Japan, USA, etc. A second drop lower become populated using the kids of that category. For instance, the very first drop lower would display USA, then California would display in the second drop lower.