Dynamic Modular Map

Hello - I am hoping that some of you brilliant people may have a suggestion for a challenge my client just faced me with:

On an HTML page, there will be a map of the U.S. - If a user picks one of 15 categories (in our case, different kinds of sports) - the map appears with gray overlays to indicate where those sports are available. Then the user rolls over the gray area, and a highlight color appears, allowing a click to a detailed HTML page.

I am looking for the most modular approach to this. I am sure I can create external MCs for each category and have them load. But, as the content changes, I am looking for a more intelligent (dynamic) approach. I don’t know where to start - variables, arrays, dynamic masking, etc.

Any input is greatly appreciated!

shorescores