US State Map
This interactive US state map displays disease surveillance data for West Nile virus, showing neuroinvasive and non-neuroinvasive case counts, deaths, and presumptive viremic blood donors by state. The choropleth map, rendered with SVG, uses a yellow-to-dark-red color scale to represent disease severity. Each state is colored based on randomly generated sample data, and hovering over a state highlights it and displays a tooltip with low, average, and high values. The map includes all 50 states plus the District of Columbia, with animated hover effects and a legend-free color encoding. The visualization is built with D3 v3 and uses a custom state path data file (uStates.js) to render the geographic boundaries.