This example displays a choropleth map of U.S. states, using darker blue fills to indicate higher population values from a hardcoded dataset for fourteen states, with unlisted states shown in light gray. It loads TopoJSON from the us-atlas package, converts it to GeoJSON with `feature`, and renders paths via `d3.geoPath` and the `d3.geoAlbersUsa` projection. A linear color scale maps population extents to a blue range, and hover tooltips appear through SVG `title` elements. The map uses D3 v7 and TopoJSON-client, with an SVG rendering approach.