Zika Virus 2015
This choropleth map visualizes Zika virus cases across the United States in 2015, with states colored on a logarithmic scale from white to black based on total reported cases. Built with D3 v3 and an Albers USA projection, the map renders each state as an SVG path, with the color encoding derived from the "Total cases" column of the dataset. States with zero cases remain white, while those with higher case counts appear progressively darker—California leads with 13 cases, followed by Florida with 9 and Texas with 8, creating a visual hierarchy of geographic impact. The map includes interactive tooltips on hover, implemented using Malcolm Maclean's tooltip pattern, and a legend adapted from Mike Bostock's example, allowing viewers to quickly identify states with higher Zika virus activity. This simple choropleth, adapted from Scott Murray's approach and earlier West Nile Virus examples, uses a log color scale to differentiate case counts across the United States.