This example displays a choropleth map of US states, with each state filled by a categorical color assigned through `d3.scaleOrdinal` and `schemeCategory10`. It renders the map using `d3.geoPath` with a `geoAlbersUsa` projection, drawing state boundaries from TopoJSON county data loaded via `d3.json`. Hovering over a state turns it green through CSS, and each state includes an SVG `<title>` element showing its name.