Fill-Rule Evenodd

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

body {
  background: steelblue;
}

.feature {
  fill-opacity: .5;
  fill-rule: evenodd;
}

.hover {
  fill: none;
  stroke: #ccc;
  pointer-events: all;
}

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

var width = 960,
    height = 500;

var path = d3.geo.path()
    .projection(d3.geo.albers()
      .rotate([72.1, 0])
      .center([0, 42.1])
      .scale(5000));

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

var feature = svg.append("g")
    .attr("class", "feature")
  .selectAll("path");

d3.json("/../../data/us.json", function(error, us) {
  if (error) throw error;

var states = topojson.feature(us, us.objects.states);

feature = feature
      .data(states.features)
    .enter().append("path")
      .style("display", "none")
      .attr("d", function(d) { return "M0,0H" + width + "V" + height + "H0Z" + path(d); });

svg.append("g")
      .attr("class", "hover")
    .selectAll("path")
      .data(states.features)
    .enter().append("path")
      .attr("d", path)
      .on("mouseover", mouseovered)
      .on("mouseout", mouseouted);
});

function mouseovered(d) {
  feature.style("display", function(p) { return d === p ? null : "none"; });
}

function mouseouted(d) {
  feature.style("display", "none");
}

</script>

Changed /mbostock/raw/4090846/us.json to a local referenece

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

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