This choropleth map shows 2021 poverty rates by US county, using a red sequential color scale to encode percentages from 0 to over 40. The visualization renders US counties as SVG paths via `d3.geoPath` and `topojson`, with state boundaries overlaid. County data comes from a USDA CSV, joined by FIPS ID, while map topology uses the `us-10m.v1` TopoJSON file. A threshold-based legend with an axis label communicates the rate categories. County-level tooltips appear on hover, though the code also appends native SVG `<title>` elements for basic interactivity.