I am not a person who can easily make sense of things in an abstract fashion. I almost always need some sort of drawing, sketch, diagram, or graph to grasp concepts and theories. This made playing around with D3.js, a data visualization library written in JavaScript, so fascinating when it was initially released more than ten years ago.

Not having looked into it much since, the coronavirus pandemic provided an opportunity to try to dabble in it again. Armed with the publicly available US-specific Covid-19 case data by the New York Times, I wanted to display the number of coronavirus cases by county on a map of the United States.

The result is based largely on adapting a couple of D3 tutorials that aim to visualize geography-based data in a similar fashion, most notably the Let’s Make a Bubble Map by D3 creator Mike Bostock, using population data.