Fit Extent by mbostock

index.html

<!DOCTYPE html>
<meta charset="utf-8">
<svg width="960" height="610"></svg>
<script src="https://unpkg.com/d3@5"></script>
<script src="https://unpkg.com/topojson-client@3"></script>
<script>

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

d3.json("https://raw.githubusercontent.com/gist/mbostock/4090846/raw/07e73f3c2d21558489604a0bc434b3a5cf41a867/us.json").then(function(us) {

  var conus = topojson.feature(us, {
    type: "GeometryCollection",
    geometries: us.objects.states.geometries.filter(function(d) {
      return d.id !== 2 // AK
        && d.id !== 15 // HI
        && d.id < 60; // outlying areas
    })
  });

  // ESRI:102004
  var path = d3.geoPath()
      .projection(d3.geoConicConformal()
          .parallels([33, 45])
          .rotate([96, 0])
          .center([0, -39])
          .fitSize([width, height], conus));

  svg.append("path")
      .datum(conus)
      .attr("d", path);
});

</script>