Almost all of the data we compile is taken directly from the websites of local or state/territory public health authorities. Where data is missing from these websites, we supplement available numbers with information from official press conferences with governors or public health authorities.
Our individual state/territory pages (accessible from our main data page) include links to current best data sources for each state, along with historical data for everything we’ve tracked, including (from March 14 forward) timestamped snapshots of the data source we used for each change.
You can see what information we’re trying to collect and what each state is currently reporting in our data completeness spreadsheet.
The COVID Tracking Project can’t offer official guidance to state health departments or compel states to report missing data. We’ve built a state grading system so state governments and their constituents can see who’s doing well and who is underperforming. We’ve built a volunteer outreach team who are in contact with authorities in every state and territory. But in the end, all we can do is ask for better and more complete data—and then ask for it again. If you’d like to see better data, you can sign up for our email list—we’ll send out guidelines on contacting your state officials to push for more transparency and better data reporting.