A colleague of mine, Ayman El-Ghazali, worked through data from the state of Maryland.

Code is available on GitHub.

I chose not source my data directly from Maryland’s State Government site because the format was not easy to use. The official Maryland Government provided data basically has each day as a column and had the rows as Zip Codes — not as easy as the data provided from the site above. So there may be few discrepancies between the data on a day to day basis, but the totals are identical. You can read about their methodologies of retrieving data from various official State Government websites and the quality of each.