This choropleth map of Maryland counties visualizes four demographic and criminal-justice metrics—incarceration count, crime count, population, and incarceration rate—using a dropdown menu to switch between them. The map renders with d3.geoMercator and d3.geoPath, coloring each county via a linear color scale over a teal-to-red palette. Tooltips display county names and values on hover, while a transition animates color changes when the metric switches. The GeoJSON data is loaded through d3.json, and the visualization is built with React, d3.v5, SVG, and animation.