New York Census Tracts by mbostock

index.html

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

.tract {
  fill: #ccc;
}

.tract:hover {
  fill: orange;
}

.tract-border {
  fill: none;
  stroke: #333;
  stroke-linejoin: round;
  stroke-linecap: round;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>

var width = 960,
    height = 700;

var path = d3.geo.path()
    .projection(null);

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

d3.json("ny.json", function(error, ny) {
  if (error) throw error;

  var tracts = ny.objects.tracts;

  // strip water counties
  tracts.geometries = tracts.geometries
    .filter(function(d) { return (d.id / 10000 | 0) !== 99; });

  svg.append("g")
    .selectAll("path")
      .data(topojson.feature(ny, tracts).features)
    .enter().append("path")
      .attr("class", "tract")
      .attr("d", path)
    .append("title")
      .text(function(d, i) { return d.id; });

  svg.append("path")
      .attr("class", "tract-border")
      .datum(topojson.mesh(ny, tracts, function(a, b) { return a !== b; }))
      .attr("d", path);
});

d3.select(self.frameElement).style("height", height + "px");

</script>

Makefile

GENERATED_FILES = \
	ny.json

all: $(GENERATED_FILES)

.PHONY: clean all

clean:
	rm -rf -- $(GENERATED_FILES) build

build/tl_2012_%_tract.zip:
	mkdir build
	curl -o $@ 'http://www2.census.gov/geo/tiger/TIGER2012/TRACT/$(notdir $@)'

build/tracts.shp: build/tl_2012_36_tract.zip
	rm -rf $(basename $@)
	mkdir -p $(basename $@)
	unzip -d $(basename $@) $<
	for file in $(basename $@)/*; do chmod 644 $$file; mv $$file $(basename $@).$${file##*.}; done
	rmdir $(basename $@)
	touch $@

ny.json: build/tracts.shp
	node_modules/.bin/topojson -o $@ --q0=0 --simplify=1 --projection='d3.geo.mercator().center([-75.819, 42.795]).scale(6193).translate([480, 350]).precision(0)' --id-property=TRACTCE -- $(filter %.shp,$^)

package.json

{
  "name": "anonymous",
  "version": "0.0.1",
  "private": true,
  "devDependencies": {
    "d3": "3",
    "topojson": "1"
  }
}