This example presents two geographic maps: a world map using the Natural Earth projection and a United States map with state population data. The world map renders all countries from a TopoJSON file using `d3.geoPath` with `d3.geoNaturalEarth1`, while the U.S. map uses `d3.geoAlbersUsa` to display state boundaries. State populations are visualized through a sequential color scale (`d3.scaleSequential` with `d3.interpolateBlues`), where values are mapped to specific state names via a static lookup object. Tooltips are added using SVG `<title>` elements to show population numbers.