D3 includes a sophisticated way to display geographical data as vector files, using either the geoJSON or topoJSON formats.
For an easy, interactive way to convert GeoJSON files into topoJSON, check out distillery.
This example is based on the Let's Make a Map article, which goes into a good bit more detail on how to use D3 for maps..
This code block is preceded by initialization code that defines parent, svg, margin, width, & height.