This interactive choropleth map visualizes 2024 Boston Marathon finisher data by state, showing participant counts, average finish times, average age, and first- versus second-half split times. The map uses d3.geoAlbers and d3.geoPath to render U.S. states from TopoJSON data, with d3.scaleLinear color scales encoding the selected metric. Hovering over a state displays a custom HTML tooltip with the detailed statistics. The code fetches external CSV data for state centers and finisher records, filtering out Puerto Rico and the U.S. Virgin Islands.