This map of the United States visualizes transportation costs by state using proportional green and grey circles, with the ten most expensive states highlighted in brown. A tooltip displays the exact cost when hovering over a circle. The chart is built with D3 v3 and topojson, using an SVG path with `path.pointRadius` to size symbols by a square-root scale. A hand-coded legend, an animated tooltip via `div.transition`, and state boundary paths rendered from TopoJSON complete the interactive display.