State Grid by mbostock

index.html

<!DOCTYPE html>
<meta charset="utf-8">
<style>

.state rect {
  fill: #dedede;
}

.state text {
  font: 12px sans-serif;
  text-anchor: middle;
}

.state--selected rect {
  fill: #9f4a6c;
}

.state--selected text {
  fill: white;
}

</style>
<svg width="960" height="500"></svg>
<script id="grid" type="text/plain">
                              ME
               WI          VT NH
WA ID MT ND MN IL MI    NY MA
OR NV WY SD IA IN OH PA NJ CT RI
CA UT CO NE MO KY WV VA MD DE
   AZ NM KS AR TN NC SC
         OK LA MS AL GA
HI AK    TX             FL
</script>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var states = [],
    selectedStates = ["MA", "MD", "ME", "MI", "MN", "MO", "MS", "MT"];

d3.select("#grid").text().split("\n").forEach(function(line, i) {
  var re = /\w+/g, m;
  while (m = re.exec(line)) states.push({
    name: m[0],
    selected: selectedStates.indexOf(m[0]) >= 0,
    x: m.index / 3,
    y: i
  });
});

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");

var gridWidth = d3.max(states, function(d) { return d.x; }) + 1,
    gridHeight = d3.max(states, function(d) { return d.y; }) + 1,
    cellSize = 40;

var state = svg.append("g")
    .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")")
  .selectAll(".state")
    .data(states)
  .enter().append("g")
    .attr("class", function(d) { return "state" + (d.selected ? " state--selected" : ""); })
    .attr("transform", function(d) { return "translate(" + (d.x - gridWidth / 2) * cellSize + "," + (d.y - gridHeight / 2) * cellSize + ")"; });

state.append("rect")
    .attr("x", -cellSize / 2)
    .attr("y", -cellSize / 2)
    .attr("width", cellSize - 1)
    .attr("height", cellSize - 1);

state.append("text")
    .attr("dy", ".35em")
    .text(function(d) { return d.name; });

</script>