A choropleth map of the United States visualizes the average house price per state, colored on a blue quantized scale from $100,000 to $800,000. The map uses `d3.geoPath` with a `geoAlbersUsa` projection to render state boundaries from US Atlas TopoJSON data, and each state’s fill is determined by price data loaded from a CSV via `d3.csv`. Interactive tooltips display the state name and price on mouseover, with the map built entirely using the D3.js library and SVG rendering.