Comparing two files with the congressional districts.
<!DOCTYPE html>
<meta charset="utf-8">
<style>
.states {
fill: #ccc;
stroke: #fff;
}
</style>
<body>
<script src="https://d3js.org/d3-array.v1.min.js"></script>
<script src="https://d3js.org/d3-geo.v1.min.js"></script>
<script src="https://d3js.org/d3-selection.v1.min.js"></script>
<script src="https://d3js.org/d3-collection.v1.min.js"></script>
<script src="https://d3js.org/d3-dispatch.v1.min.js"></script>
<script src="https://d3js.org/d3-request.v1.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="d3-composite-projections.js"></script>
<script>
var width = 960,
height = 500;
var projection = d3.geoAlbersUsaTerritories();;
var path = d3.geoPath()
.projection(projection);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
svg.append("path")
.datum({type: "Sphere"})
.attr("d", path)
.style("fill","#eee");
d3.json("us_congress.json", function(error, congress) {
d3.json("us_territories.json", function(error, us) {
svg.append("path")
.attr("class", "us")
.datum(topojson.feature(us, us.objects.us))
.attr("d", path)
.style("fill","#f33");
svg.append("path")
.attr("class", "us")
.datum(topojson.feature(congress, congress.objects.cgd114p010g))
.attr("d", path)
.style("fill","#33f")
.style("opacity",0.5);
});
});
</script>