Curious... this thread ended out here!
I agree with GunChleoc here.
Indeed I would go further and dispense with the map and have a simple, text-based, hierarchal, by-state directory.
That said, whatever method is chosen, let's examine the practicalities.
(DISCLAIMER: This is based on my own experience with server systems; it's simply a summary of what may be required - it's not me volunteering, but then you knew that, right?)
For the sake of clarity, I'll call it "The directory" - whether it's text-based or a map.
The first choice is; static or dynamic.
Static: All entries in the directory are manually maintained. Simple to set up, a potential nightmare to keep current. Every time a member joins, or someones membership expires, the directory has to be changed, and the page uploaded

Dynamic: All entries in the directory are linked to a back-end database through server-side scripting. More difficult to set up and customise, but any changes to the membership database are automatically reflected in the directory whenever someone opens the page. Of course, this still relies on someone (or someones) maintaining the membership database! And this assumes that the database is maintained on the host in a compatible database - if not, the database would need to be uploaded and, very likely, converted to the host-based database format.
(I am assuming that there is a membership database kept somewhere!)
Since I am not privy to the back-end details or the site (beyond what I can see; it uses a Content Management System (CMS), hosted at theplanet.com in Texas, and hopefully runs on a Unix platform, as all good sites should!), perhaps Rudy can give us more details, and give his opinion on the practicalities of having such a dynamic directory on the site, and what facilities exist for scripting?
If you go with a map, then there's the added problem of taking that data and generating a graphical representation of it; tools exist out there for this, but would they be available on the hosting server?
So, before we run off and start creating a map, let's find out what's even possible on the server. I'm really not trying to be negative (for a change), but it's often easy to say "hey, let's do this!" and then discover what you're getting yourself into!