This choropleth map colors US states by average annual sunshine hours, using a yellow-green sequential scale. The data is stored in a JavaScript Map for approximately 20 states, with missing states rendered pale green. Built with D3 v7 and topojson-client, it uses `d3.geoAlbersUsa()` for projection, `d3.geoPath()` for rendering state boundaries, and a custom tooltip on mouse events. The legend is drawn inside the SVG, and state data comes from the us-atlas states-10m GeoJSON.