This example displays a vector map of Toronto using topojson data from a GitHub repository. The map is rendered as SVG paths via `d3.geoPath` and the `geoNaturalEarth1` projection, with React managing the component structure. City boundaries appear as teal strokes without fill or labels, while the `useData` hook loads and converts the TopoJSON to GeoJSON using `feature` from topojson. The visualization uses d3.v5 and React 16.9, with the mark component generating one path per feature.