class 3 - states // source http://jsbin.com/liqono

<!DOCTYPE html>
<meta charset="utf-8">
<title>class 3 - states</title>
<style>
body {
  position: absolute;
  margin: 0px;
}
svg {
  background-color: #4682b4;
}

.info {
  font-family: sans-serif;
  color: #000;
  position: absolute;
  top: 450px;
  left: 800px;
}
path {
  fill: #555555;
  stroke: #aaaaaa;
}
</style>
<h3>Map Showing Earthquakes in US</h3>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/topojson.v2.min.js"></script>

<body>

d3.json(url, plotStates);
function plotStates(error, json) {
  // Create array of GeoJSON features -- this defines the global variable "data"
  data = json.objects.us.geometries.map(function(d) { return topojson.feature(json, d); })
  // Put your code here
  // Plot the features
  layer.selectAll("path")
      .data(data)
    .enter()
      .append("path")
      .attr("d", path);
}
function mousemoved() {
  info.text(formatLocation(projection.invert(d3.mouse(this)), projection.scale()));
}
function formatLocation(p, k) {
  var format = d3.format("." + Math.floor(Math.log(k) / 2 - 2) + "f");
  return (p[1] < 0 ? format(-p[1]) + "°S" : format(p[1]) + "°N") + " "
       + (p[0] < 0 ? format(-p[0]) + "°W" : format(p[0]) + "°E");
}

var map;
function initMap() {
  map = new google.maps.Map(document.getElementById('map'), {
    zoom: 2,
    center: new google.maps.LatLng(2.8,-187.3),
    mapTypeId: 'terrain'
  });

// Create a <script> tag and set the USGS URL as the source.
  var script = document.createElement('script');
  // This example uses a local copy of the GeoJSON stored at
  // https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/2.5_week.geojsonp
  script.src = 'https://developers.google.com/maps/documentation/javascript/examples/json/earthquake_GeoJSONP.js';
  document.getElementsByTagName('head')[0].appendChild(script);
}

// Loop through the results array and place a marker for each
// set of coordinates.
window.eqfeed_callback = function(results) {
  for (var i = 0; i < results.features.length; i++) {
    var coords = results.features[i].geometry.coordinates;
    var latLng = new google.maps.LatLng(coords[1],coords[0]);
    var marker = new google.maps.Marker({
      position: latLng,
      map: map
    });
  }
}

</script>

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

https://d3js.org/topojson.v2.min.js