This choropleth map displays the counties of Massachusetts, with each town colored according to its assigned county via a categorical color scale. A conic conformal projection (d3.geoConicConformal) is used to render the state’s boundaries, while d3.geoPath draws the polygons from a TopoJSON source. Town-to-county mappings are loaded from a CSV file, and the color scale is a d3.scaleOrdinal. The visualization is built with React, using d3.v5 for geographic and data processing, and outputs as SVG paths.