[UNLISTED] helping someone

<html><head><meta charset="utf-8">
<style>
.county-boundary {
  fill: #aaa;
  stroke: #fff;
  stroke-width: .5px;
}

.county-boundary:hover {
  fill:orange;
}

.state:hover {
  fill-opacity:0;
}

</style>

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

var width = 960,
    height = 500,
    centered;

var margins = { left: 0, top: 0, right: 0, bottom: 0 };

var projection = d3.geo.albersUsa()
    .scale(1070)
    .translate([width / 2, height / 2]);

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

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

var g = svg.append("g");

var countiesG = g.append("g")
    .attr("id", "counties");

// Make sure circles appear in front of counties.
var circlesG = g.append("g")
    .attr("id", "circles");

d3.csv("eq_subset.csv", function(rawData) {
  d3.json("us.json", function(error, us) {

function display_points (geometry) {

var data_subset = data.filter(function(d) {

// geometry.coordinates is an array of polygons,
        // so we need to check each one separately.
        return !geometry.coordinates.every(function (polygon){
          return !d3.polygonContains(polygon, [d.Longitude, d.Latitude]);
        });
      });

var circles = circlesG
        .selectAll('circle')
          .data(data_subset);

circles
        .enter()
        .append('circle');

circles
        .attr({
            cx: function (d) { return projection([d.Longitude,d.Latitude])[0]; },
            cy: function (d) { return projection([d.Longitude,d.Latitude])[1]; },
            r: 3
        })
        .attr('fill','black');

circles.exit().remove();
    }

countiesG
      .selectAll("path")
        .data(topojson.feature(us, us.objects.counties).features)
      .enter().append("path")
        .attr("d", path)
        .attr("class", "county-boundary")
        .on("mouseover", function(d) {
          return display_points(d.geometry);
        });

});
});
</script>
</body>
</html>

https://d3js.org/d3.v3.min.js

https://d3js.org/d3-polygon.v1.min.js

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