Measuring the Impact of COVID-19: A Different Approach to Mapping the Virus *Updated*

Justin Tischler

As COVID-19 continues its march across the country, it can be difficult for those not yet affected to understand how quickly this virus is spreading. We have been mapping the positive test cases since the outbreak started in March, and this week we have added data to visualize California, Florida and Louisiana.

The maps and associated visualizations most commonly utilized by the media to depict case counts draw a lot of attention to current urban epicenters in the U.S. – especially New York.  However, those maps can be somewhat misleading in that they minimize the risk faced by less populated areas. A thorough review of the data suggests that suburban, exurban, and rural communities should be aware of and prepared for the emerging threat.

As an academic exercise to help several communities close to our hearts, we mapped county-level case counts compiled and made available by the New York Times along with population counts supplied by Synergos Technologies .

Our time-series maps allow you to visualize case penetration rates for select states and their surrounding areas, measured as the number of cases per 100,000 people.  We chose penetration rates because this approach gets closest to measuring “how likely is the average person in my community to carry this?”.  A case penetration rate of 1,000 means that 1% of the population in that county has tested positive for COVID-19.

We do want to call out several caveats associated with this data:

  • This data is limited to confirmed (positive) cases only
  • Increased testing is highly likely to increase case rates, just as a lack of testing is highly likely to suppress case rates. Testing rates differ over time and from state to state
  • Areas of low population might be expected to realize a spike in case penetration rates from small case numbers in the early stages of transmission
  • Our updated maps include data through April 15


Michigan and Surrounding Areas


Texas and Surrounding Areas





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