LEX GRAPI

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Percentage of population w/ GRAPI >30%</title>
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
<script src="https://cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.5/leaflet.min.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/calvinmetcalf/leaflet-ajax/gh-pages/dist/leaflet.ajax.min.js"></script>

<link rel="stylesheet" href="https://cdn.leafletjs.com/leaflet-0.7.5/leaflet.css" />
<style>
  body { margin:0; padding:0; }
  #map { position:absolute; top:0; bottom:0; width:100%; }
  .info {
    padding: 6px 8px;
    font: 14px/16px Arial, Helvetica, sans-serif;
    background: white;
    background: rgba(255,255,255,0.8);
    box-shadow: 0 0 15px rgba(0,0,0,0.2);
    border-radius: 5px;
    max-width: 300px;
}
.info h4 {
    margin: 0 0 5px;
    color: #000;
}
  .legend {
    line-height: 18px;
    color: #000;
    max-width: 200px;
}
.legend i {
    width: 18px;
    height: 18px;
    float: left;
    margin-right: 8px;
    opacity: 0.7;
}
.legend h4 {
	padding: 0;
	margin: 0;
}
</style>
</head>
<body>
<div id='map'></div>
<script>
var map = L.map('map')
    .setView([38.046408, -84.497083], 11);

var grapi;
var info = L.control();

info.onAdd = function (map) {
    this._div = L.DomUtil.create('div', 'info'); // create a div with a class "info"
    this.update();
    return this._div;
};

info.update = function (props) {
    this._div.innerHTML = (props ?
        '<b>Tract ' + props.TRACTCE + ', Blockgroup ' + props.BLKGRPCE + '</b><br />' + props.TtlAbv30 + ' people or ' + props.PrcntAbv30 + '% of the population have a gross rent as percent of income greater than 30%'
        : 'Hover over a blockgroup');
};

info.addTo(map)

function highlightFeature(e) {
    var layer = e.target;

layer.setStyle({
        weight: 5,
        color: '#666',
        dashArray: '',
        fillOpacity: 0.7
    });

if (!L.Browser.ie && !L.Browser.opera) {
        layer.bringToFront();
    }
    info.update(layer.feature.properties);
}

function resetHighlight(e) {
	grapi.resetStyle(e.target);
	info.update();
}

function zoomToFeature(e) {
    map.fitBounds(e.target.getBounds());
}

function onEachFeature(feature, layer) {
    layer.on({
        mouseover: highlightFeature,
        mouseout: resetHighlight,
        click: zoomToFeature
    });
}

function getColor(d) {
	return d > 60 ? "#d7191c":
		d > 45 ? "#fdae61":
		d > 30 ? "#ffffbf":
		d > 15 ? "#abd9e9":
		d >= 0 ? "#2c7bb6":
			"#fff";
}

function style(feature) {
	return {
		fillColor:getColor(feature.properties.PrcntAbv30),
		weight: 1,
		opacity: 1,
		color: "white",
		fillOpacity: 0.6
	}
}

grapi = new L.GeoJSON.AJAX("https://gist.githubusercontent.com/maptastik/af28869a22d3947b7767/raw/36af6213ccb7c7ef909cb4e038963de6ab489ae9/grapi.geojson", {
      style: style,
      onEachFeature: onEachFeature
    }).addTo(map);

var legend = L.control({position: 'bottomright'});
legend.onAdd = function (map) {
	var div = L.DomUtil.create('div', 'info legend'),
	grades = [0, 15, 30, 45, 60],
	labels = [];
	div.innerHTML = '<h4>% of population where GRAPI > 30% (2013)</h4><br>'
	for (var i = 0; i < grades.length; i++) {
		div.innerHTML += '<i style="background:' + getColor(grades[i]+1) + '"></i> ' + grades[i] + (grades[i + 1] ? '&ndash;' + grades[i+1] + '<br>' : '+');
	}

return div;
};
legend.addTo(map);
</script>
</body>
</html>

Modified http://cdn.leafletjs.com/leaflet-0.7.5/leaflet.js to a secure url

Updated missing url https://cdn.rawgit.com/calvinmetcalf/leaflet-ajax/gh-pages/dist/leaflet.ajax.min.js to https://cdn.jsdelivr.net/gh/calvinmetcalf/leaflet-ajax/gh-pages/dist/leaflet.ajax.min.js

https://cdn.leafletjs.com/leaflet-0.7.5/leaflet.js

https://cdn.rawgit.com/calvinmetcalf/leaflet-ajax/gh-pages/dist/leaflet.ajax.min.js