us_map_unemployment

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

.counties {
  fill: none;
  stroke: #fff;
}

.states {
  fill: none;
  stroke: #fff;
  stroke-linejoin: round;
}

#neighborhoodPopover {
  position: absolute;
  text-align: center;
  padding: 2px;
  font-family: futura;
  font-size: 12px;
  background: #fff;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
  opacity: 0;
}

.q0-9 { fill:rgb(247,251,255); }
.q1-9 { fill:rgb(222,235,247); }
.q2-9 { fill:rgb(198,219,239); }
.q3-9 { fill:rgb(158,202,225); }
.q4-9 { fill:rgb(107,174,214); }
.q5-9 { fill:rgb(66,146,198); }
.q6-9 { fill:rgb(33,113,181); }
.q7-9 { fill:rgb(8,81,156); }
.q8-9 { fill:rgb(8,48,107); }

</style>
<svg width="960" height="600"></svg>
<div id='neighborhoodPopover'> </div>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>

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

var rateById = d3.map();

var quantize = d3.scaleQuantize()
    .domain([0, 0.15])
    .range(d3.range(9).map(function(i) { return "q" + i + "-9"; }));

var projection = d3.geoAlbersUsa()
    .scale(1280)
    .translate([width / 2, height / 2]);

var path = d3.geoPath()
    .projection(projection);

d3.queue()
    .defer(d3.json, "us.json")
    .defer(d3.json, "california.json")
    .defer(d3.json, "sf.json")
    .defer(d3.tsv, "unemployment.tsv", function(d) { rateById.set(d.id, +d.rate); })
    .await(ready);

function ready(error, us) {
  if (error) throw error;

svg.append("g")
      .attr("class", "counties")
    .selectAll("path")
      .data(topojson.feature(us, us.objects.counties).features)
    .enter().append("path")
      .attr("class", function(d) { return quantize(rateById.get(d.id)); })
      .attr("d", path)
      .on("mouseenter", function(d) {
        console.log(d);
      d3.select(this)
      .style("stroke-width", 1.5)
      .style("stroke-dasharray", 0)

d3.select("#neighborhoodPopover")
      .transition()
      .style("opacity", 1)
      .style("left", (d3.event.pageX) + "px")
      .style("top", (d3.event.pageY) + "px")
      .text(rateById.get(d.id))

})
    .on("mouseleave", function(d) {
      d3.select(this)
      .style("stroke-width", .25)
      .style("stroke-dasharray", 1)

d3.select("#neighborhoodPopovercountyText")
      .transition()
      .style("opacity", 0);
    });

svg.append("path")
      .datum(topojson.mesh(us, us.objects.counties.id, function(a, b) { return a !== b; }))
      .attr("class", "counties")
      .attr("d", path);
}

console,log(us);

</script>

https://d3js.org/d3.v4.min.js

https://d3js.org/topojson.v1.min.js