This visualization shows the 2012 U.S. presidential election results at the county level using a value-by-alpha choropleth, where each county’s fill opacity reflects the winning candidate’s margin of victory. Built with D3 v4 and rendered as an SVG animation, the map encodes data from the included TopoJSON file, with counties colored by winner and opacity scaled by vote share. The visualization updates smoothly via animated transitions, making the geographical distribution of Democratic and Republican support easy to compare across the country.