An interactive property tax calculator displays U.S. state tax rates on a choropleth map, with users able to enter a property value and select a state via dropdown or map click to see estimated annual and monthly taxes. The visualization uses D3.js v7 with `d3.geoAlbersUsa` and TopoJSON for map rendering, `d3.scaleSequential` for color encoding, and SVG paths with hover tooltips and click interactions. Real-time calculations update from a CSV dataset of 2024 state averages, with optional custom rate input.