Geojson file used for the map can be found here: https://eric.clst.org/tech/usgeojson/
Background image from: https://www.toptal.com/designers/subtlepatterns/binding-dark/
Styling references: http://bl.ocks.org/lwhitaker3/e8090246a20d9515789b (tooltips) https://bl.ocks.org/officeofjane/9b9e606e9876e34385cc4aeab188ed73 (slider)