TopoJSON Oil and Gas Map

<!DOCTYPE html>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>

h1, h2 {
  font-family: "Liberation Mono", "Lato", "Open Sans", "sans-serif";
  color: #fff;
  margin: 0px;
  padding: 3px;
}

body {background: #1a1a1a; -webkit-text-size-adjust: none;}

.counties {
  fill: none;
  stroke: rgb(44, 44, 44);
}

.counties path:hover {
  fill:red;
  transition-delay: 0ms;}

.states {
  fill: none;
  stroke: #1a1a1a;
  stroke-linejoin: round;
  stroke-width: 1.5;
}

.axis path {stroke: none; fill: none;}
.axis line {stroke: #fff; fill: none;}
.tick text {
  stroke: #fff;
  fill: #fff;
  font-family: "Liberation Mono", "Lato", "Open Sans", "sans-serif";
  font-size: 1.7em;
  text-shadow: none;
  }

.d3-tip {
  font-family: "Liberation Mono", "monospace";
  position: absolute;
  line-height: 1.2;
  padding: 12px;
  background: rgba(0, 0, 0, 0.8);
  color: #fff;
  border-radius: 3px;
}

</style>

<div class="text-things">
        <h1>US Weekly Oil and Gas Rig Count</h1>
        <h2>June 25, 2021</h2>    
    </div>
    
<svg height="700" width="1000"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/d3-scale-chromatic.v0.3.min.js"></script>
<script src="https://d3js.org/topojson.v2.min.js"></script>
<script src="d3-tip.js"></script>
<script>
// Template: https://bl.ocks.org/mbostock/4060606
// Legend 1: https://www.visualcinnamon.com/2016/05/smooth-color-legend-d3-svg-gradient.html
// Legend 2: https://bl.ocks.org/nbremer/5cd07f2cb4ad202a9facfbd5d2bc842e

// The drawing board and its dimensions
var svg = d3.select("svg"),
    margin = { top: 0, bottom: 0, right: 0, left: 0},
    width = +svg.attr("width"),
    height = +svg.attr("height");

//Append a defs (for definition) element to your SVG
var defs = svg.append("defs"),
    legend = svg.append("g")
      .attr("class", "legendWrapper")
      .attr("transform", "translate(" + width / 3 + ",0)")

//Append a linearGradient element to the defs and give it a unique id
var linearGradient = defs.append("linearGradient")
    .attr("id", "linear-gradient");

// Maps to hold data
var total = d3.map(),
    oil   = d3.map(),
    gas   = d3.map();

// Tool-tip
var tip = d3.tip()
    .attr("class", "d3-tip")
    .offset(function() {
      return [0 , 0]
    })
    .html(function(d) {
      return "Location: " + d.properties.display_name  +
      "<br>Rigs: "  + (total.get(d.properties.location) == null ? 0 : total.get(d.properties.location)) +
      "<br>Oil: \xa0" + (oil.get(d.properties.location) == null ? 0 : oil.get(d.properties.location)) +
      "<br>Gas: \xa0" + (gas.get(d.properties.location) == null ? 0 : gas.get(d.properties.location));
      });

svg.call(tip);

// Set a queue awaiting on function ready()
// This contains data and pre-processing instructions (i.e. adding data to the Maps)
d3.queue()
    .defer(d3.json, "us.json")
    .defer(d3.csv, "rig_counts.csv", function(d) {
         total.set(d.location, +d.Total);
         oil.set(d.location, +d.Oil);
         gas.set(d.location, +d.Gas); 
         })
    .await(ready);

// Here is where it all happens: the ready() function
function ready(error, us) {
  if (error) throw error;

// Create a path generator whose projection
  // is an Albers Equal Area and whose drawable
  // area is defined by the width and margins
  // of the SVG.
  var path = d3.geoPath()
      .projection(d3.geoAlbers()
          .fitExtent([[margin.left, margin.top], [width - margin.right, height - margin.bottom]],
                     topojson.feature(us, us.objects.states))
      );

var timeout;

// Color map.
  // Sequential viridis whose domain is the extent (min/max) of the total rig count values.
  var colScale = d3.scaleSequential(d3.interpolateViridis)
      .domain(d3.extent(total.values()));

//Draw the rectangle and fill with gradient
  var legendBar = legend.append("rect")
    .attr("width", 350)
    .attr("height", 20)
    .style("fill", "url(#linear-gradient)");

//Append multiple color stops by using D3's data/enter step
/*  linearGradient.selectAll("stop")
    .data(topojson.feature(us, us.objects.counties).features)
    .enter().append("stop")
    .attr("offset", function(d,i) { return i / (69 - 1); })
    .attr("stop-color", function(d) { return colScale(total.get(d.properties.location)); });
*/

linearGradient
    .attr("x1", "0%")
    .attr("y1", "0%")
    .attr("x2", "100%")
    .attr("y2", "0%");
  
  linearGradient.selectAll("stop")
    .data([
        {offset: "0%",    color: "#440154FF"},
        {offset: "12.5%", color: "#472D7BFF"},
        {offset: "25%",   color: "#3B528BFF"},
        {offset: "37.5%", color: "#2C728EFF"},
        {offset: "50%",   color: "#21908CFF"},
        {offset: "62.5%", color: "#27AD81FF"},
        {offset: "75%",   color: "#5DC863FF"},
        {offset: "87.5%", color: "#AADC32FF"},
        {offset: "100%",  color: "#FDE725FF"}
      ])
    .enter().append("stop")
    .attr("offset", function(d) { return d.offset; })
    .attr("stop-color", function(d) { return d.color; });
  
  //Set scale for x-axis
  var xScale = d3.scaleLinear()
	  .range([0, 350])
	  .domain(d3.extent(total.values()));

//Define x-axis
  var xAxis = d3.axisBottom()
	  .ticks(5)  //Set rough # of ticks
	  //.tickFormat(formatPercent)
	  .scale(xScale);

//Set up X axis
  legend.append("g")
	.attr("class", "axis")  //Assign "axis" class
	.attr("transform", "translate(0,20)")
	.call(xAxis);

svg.append("g")
      .attr("class", "counties")
    .selectAll("path")
    .data(topojson.feature(us, us.objects.counties).features)
    .enter().append("path")
    .attr("fill", function(d) {
        if (total.get(d.properties.location) == null) {
          return "#4d4d4d";
      } else {
        return colScale(total.get(d.properties.location)); 
        }})
      .attr("d", path)
    // tooltip mouseover behavior
    .on("mouseover", function(d) {
      var context = this;
      var args = [].slice.call(arguments);
      args.push(this);
      clearTimeout(timeout);
      timeout = setTimeout(function() {
        tip.show.apply(context, args);
        }, 100);
    })
    // tooltip mouseout behavior
    .on("mouseout", function(d) {
      clearTimeout(timeout);
      tip.hide(d);
    });

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

</script>

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

https://d3js.org/d3-scale-chromatic.v0.3.min.js

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