A proportional symbol map shows the average grocery cost per state across the U.S., with circle area scaled to cost and states in the top ten for cost highlighted in red. Built with D3 v3, it uses the `d3.geo` Albers projection and `topojson` for the state outlines, while `d3.scale.sqrt` maps cost values to circle radii. Hovering a circle reveals a tooltip with the state name and cost, and the underlying data is loaded from a CSV file.