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MD Counties with US Atlas

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MMTClass
Last edited Apr 30, 2017
Created on Apr 29, 2017

This choropleth map of Maryland counties visualizes population density using a conic conformal projection fitted to GeoJSON county boundaries. The code loads topojson and population data, calculates density as population divided by land area, and fills each county with colors from the d3.schemeOrRd sequential color scheme via d3.scaleThreshold. Hover interactions highlight counties in red. A legend built with d3.axisBottom and d3.scalePow shows the density thresholds. The visualization uses d3.v4, topojson.v2, and renders SVG paths with d3.geoPath, sourced from UMBC VIS class data.

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