What is the best way to model and visualize geographical data for web?

I want to make a web app that consists of the following:

There is a map of the world with current geographical areas (countries, territories, etc) highlighted. Next to the map is a slider which the user can move to change the time period. The map updates the highlighted areas based on the selected year.

So a couple of questions. First of all, what would be the best way to model the data. Would it be best to have each area defined by its borders as a series of vectors?

Also, from a performance standpoint, what would be the best way to render the map? Would re-rendering an SVG take too long?