Choropleth Map
A choropleth map of United States states renders geographic boundaries as SVG paths, colored light blue with black outlines and a red hover state. The map uses the topojson library to convert US Atlas TopoJSON data into GeoJSON features, then projects them with d3.geoAlbersUsa and renders them via d3.geoPath. Interactive zooming is enabled through a d3.zoom event that applies transform updates to the map group, while a categorical color legend displays the domain. State data loads from a remote US Atlas JSON file.