D3 Examples - A simple vector map of Vermont's Counties.

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<!DOCTYPE html>
<meta charset="utf-8">
<style>
  .county-boundary {
        fill: none;
        stroke: #777;
        stroke-dasharray: 2,2;
        stroke-linejoin: round;
    }
    .state-boundary {
        fill: none;
        stroke: none;
        stroke-linejoin: round;
    }
​
    text {
        font-family: helvetica;
        fill: black;
        font-weight: 300;
        text-anchor: middle;
    }
​
</style>
<body>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script src="https://d3js.org/topojson.v1.min.js"></script>
<script>
​
var width = 960,
    height = 700;
​
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);
​
var projection = d3.geo.mercator()
​
var path = d3.geo.path()
    .projection(projection);
​
d3.json("vt-counties.json", function(error, vt) {
​
    var vermont = topojson.feature(vt, vt.objects.counties);
​
    projection
        .scale(1)
        .translate([0, 0]);
​
    var b = path.bounds(vermont),
        s = .95 / Math.max((b[1][0] - b[0][0]) / width, (b[1][1] - b[0][1]) / height),
        t = [(width - s * (b[1][0] + b[0][0])) / 2, (height - s * (b[1][1] + b[0][1])) / 2];
​
    projection
        .scale(s)
        .translate(t);
​
​
    svg.selectAll(".counties")
        .data(topojson.feature(vt, vt.objects.counties).features)
        .enter().append("path")
            .attr("class", function(d) {return "county " + d.properties.name;})
            .attr("d", path)
            .style("fill", "white")
                .transition()
                .duration(3000)
            .style("fill", "#ddc");
​
​
    svg.append("path")
        .datum(topojson.mesh(vt, vt.objects.counties, function(a, b){return a !== b; }))
        .attr("d", path)
        .attr("class", "county-boundary");
​
    svg.selectAll(".county-label")
        .data(topojson.feature(vt, vt.objects.counties).features)
    .enter().append("text")
        .attr("transform", function(d) { return "translate(" + path.centroid(d) + ")"; })
        .attr("dy", ".35em")
        .text(function(d) { return d.properties.name; })
        .style("font-size", "0px")
            .transition()
            .delay(3500)
        .style("font-size", "12px");
​
});
​
d3.select(self.frameElement).style("height", height + "px");
​
</script>
    