Mapping The National Register of Historic Places: Part I (New York)

<!DOCTYPE html>
<meta charset="utf-8">
<link href="https://fonts.googleapis.com/css?family=Sorts+Mill+Goudy:400,400italic" rel="stylesheet" type="text/css">
<style>

body {
	background-color: #4DD0E1;
	font-family: Futura;
}

.circle {
	fill:red;
}

.land {
  fill: #222;
}

.county-boundary {
  fill: none;
  stroke: #fff;
  stroke-width: .5px;
}

.state-boundary {
  fill: none;
  stroke: #fff;
}

</style>
<body>
<svg width="960" height="600"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/topojson.v2.min.js"></script>
<script src="https://d3js.org/topojson.v1.min.js"></script>
<script>

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

var projection = d3.geoAlbersUsa()
    .scale(1280)
    .translate([width / 2, height / 2]);

var path = d3.geoPath()
    .projection(projection);

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

svg.append("path", ".graticule")
      .datum(topojson.mesh(us, us.objects.counties, function(a, b) { return a !== b && !(a.id / 1000 ^ b.id / 1000); }))
      .attr("class", "county-boundary")
      .attr("d", path);

svg.append("path", ".graticule")
      .datum(topojson.mesh(us, us.objects.states, function(a, b) { return a !== b; }))
      .attr("class", "state-boundary")
      .attr("d", path);
})

d3.csv("National_Register_of_Historic_Places.csv", function(data) {

d3.nest()
					.key(function(d) { return d.Longitude; })
					.key(function(d) { return d.Latitude; })
					.map(data);

console.log(data);
			
			svg.selectAll("circle")
			   .data(data)
			   .enter()
			   .append("circle")
			   .attr("cx", function(d) {
				   return projection([d.Longitude, d.Latitude])[0];
			   })
			   .attr("cy", function(d) {
				   return projection([d.Longitude, d.Latitude])[1];
			   })
			   .attr("r", "2px")
			   .style("fill", "#F4D03F")
			   .style("opacity", 0.75)
			   .attr("d", path);
			
		});

</script>

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

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

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