This example demonstrates a two-level drilldown choropleth map of India, showing state boundaries upon initial load and transitioning to district-level boundaries when a state is clicked. The visualization uses React for component state management, with D3 geoMercator projection and geoPath for rendering SVG shapes, and applies a zoom-to-bounding-box transition via d3.zoom and zoomIdentity. The map animates through a 500-millisecond transition, scaling and translating the viewport to focus on the selected region’s geometry, with data fetched from TopoJSON files for both state and district outlines.