The map displays the University Diversity Index for each U.S. state, using a white-to-blue color scale where darker shades indicate higher diversity. It is rendered as an SVG using `d3.geoPath` and `d3.geoAlbersUsa` with data from a JSON file. On mouseover, a histogram image for the hovered state appears, which is appended dynamically and follows the cursor. The visualization is built with React, D3 v4, and the `d3-legend` library for the color legend.