We're trying something a bit experimental for visualizing the progression of the coronavirus pandemic within the United States, where we've combined Johns Hopkins' available time series data for the viral infection, which begins on 10 March 2020 for individual U.S. states, with the "tower" format the South China Morning Post developed to illustrate the relative speed of spread and scope of COVID-19 cases, recoveries, and deaths occurring within Hong Kong since its first case was detected.
Unlike the SCMP's presentation, we've indexed the relative size of the tower elements to correspond to the percentage of each state's population, which should make it very easy to visually compare the relative severity of coronavirus infections between individual states, since all charts can share the same scale.
We're taking this "skyline" chart concept for a test drive for the six U.S. states or territories reporting the highest percentage of cases among their populations, showing all the daily data for each through 18 March 2020. These charts cover Colorado, Louisiana, Massachusetts, New Jersey, New York, Washington, and the District of Columbia. The charts can be viewed here.
We recognize that at this point in time, the data isn't communicating the rate of spread of the coronavirus so much as it is indicating the rate at which testing is being expanded and capturing already existing cases within the population, which you can certainly see with New York's data. Meanwhile, the number of confirmed cases doesn't always grow each day, where the cumulative total may be adjusted if cases are reclassified, perhaps because of errors, as appears to have happened with Washington's data between 17 March 2020 and 18 March 2020.
Since the U.S. is still in the early phase of tracking coronavirus cases, there aren't yet many reports of recovered patients among the confirmed cases. As these numbers grow, they will 'fill out' each state's tower from the center outward. Deaths will be treated similarly, which are only large enough as a percent of the state's population to be visible in Washington's tower chart at this time.
As the number of confirmed cases grows, we will periodically adjust the scaling of the charts to accommodate the data in future posts on the topic.