MapBox + d3

<!DOCTYPE html>
<html>
<head>
  <script src='https://api.tiles.mapbox.com/mapbox.js/v0.6.4/mapbox.js'></script>
  <script src='https://d3js.org/d3.v2.min.js?2.9.3'></script>
  <link
      href='https://api.tiles.mapbox.com/mapbox.js/v0.6.4/mapbox.css'
      rel='stylesheet' />
  <style>
    body { margin:0; padding:0; }
    #map { position:absolute; top:0; bottom:0; width:100%; }
    .d3-vec { position:absolute; }
    path {
      fill: #000;
      fill-opacity: .2;
      stroke: #fff;
      stroke-width: 1.5px;
    }

path:hover {
      fill: brown;
      fill-opacity: .7;
    }
  </style>
</head>
<body>
<div id='map'></div>
<script>
  function folly() {
      var f = {}, bounds, feature;
      var div = d3.select(document.body)
          .append("div")
          .attr('class', 'd3-vec'),
      svg = div.append('svg'),
      g = svg.append("g");

f.parent = div.node();

// Use Leaflet to implement a D3 geographic projection.
      f.project = function(x) {
        var point = f.map.locationPoint({ lat: x[1], lon: x[0] });
        return [point.x, point.y];
      }

// Reposition the SVG to cover the features.
      f.draw = function() {
        var bounds = f.map.extent(),
            bl = bounds.southWest(),
            tr = bounds.northEast();
        var bottomLeft = f.project([bl.lon, bl.lat]),
            topRight = f.project([tr.lon, tr.lat]);

svg.attr("width", topRight[0] - bottomLeft[0])
            .attr("height", bottomLeft[1] - topRight[1])
            .style("margin-left", bottomLeft[0] + "px")
            .style("margin-top", topRight[1] + "px");

g.attr("transform", "translate(" + -bottomLeft[0] + "," + -topRight[1] + ")");

path = d3.geo.path().projection(f.project);

feature.attr("d", path);
      }

f.data = function(collection) {
          bounds = d3.geo.bounds(collection);
          feature = g.selectAll("path")
              .data(collection.features)
              .enter().append("path");
          return f;
      };

return f;
  }
  mapbox.auto('map', 'examples.map-vyofok3q', function(map) {
      d3.json("us-states.json", function(collection) {
          var l = folly().data(collection);
          map.addLayer(l);
          map.zoom(4).center({ lat: 37, lon: -90 });
      });
  });
</script>
</body>
</html>

Modified http://api.tiles.mapbox.com/mapbox.js/v0.6.4/mapbox.js to a secure url

Modified http://d3js.org/d3.v2.min.js?2.9.3 to a secure url

https://api.tiles.mapbox.com/mapbox.js/v0.6.4/mapbox.js

https://d3js.org/d3.v2.min.js?2.9.3