Annotations on COVID-19 state data definitions as of March 7, 2021

The COVID Tracking Project was a volunteer organization launched from The Atlantic and dedicated to collecting and publishing the data required to understand the COVID-19 outbreak in the United States. Our dataset was in use by national and local news organizations across the United States and by research projects and agencies worldwide.
In the US, health data infrastructure has always been siloed. Fifty-six states and territories maintain pipelines to collect infectious disease data, each built differently and subject to different limitations. The unique constraints of these uncoordinated state data systems, combined with an absence of federal guidance on how states should report public data, created a big problem when it came to assembling a national picture of COVID-19’s spread in the US: Each state has made different choices about which metrics to report and how to define them—or has even had its hand forced by technical limitations.
Those decisions have affected both The COVID Trac...