This choropleth maps road accident deaths across Russian regions, using a threshold color scale from light green to dark red, and includes interactivity where hovering highlights a region and displays its name and fatality count on a tooltip. It also plots major cities as points and includes a vertical legend. Built with D3.js v3, it uses the `d3.geo.albers` projection and `d3.geo.path` to render the map geometries from TopoJSON, while `d3.csv` and `d3.tsv` load the accident and city data, and SVG shapes, transitions, and the `d3.select` API handle the visualization and mouseover effects.