The political data was obtained from Harvard Dataverse. A county was assumed to be a swing county if it did not vote for the same party in the presidential election for all of 2008, 2012, and 2016. If the county majority did vote for the same party, then it was assigned to the corresponding party.
The political data was obtained from ncov19.us . This provided daily updates on Coronavirus cases by county. The website should remain up to date, each day gathering the latest day's cases, and incorporating them into the map.
Cases in American Indian Land and US territories were not counted in the map. American Indian lands count for 5000 to 10000 cases that are missing, but where citizens can vote for president. Washington D.C. and New York Boroughs are not displayed on the map, but are counted in all relevant graphs. Some states also list prisoners and visitors separately. Many of those incarcerated are ineligible to vote, but visitors are almost certainly lost for analysis purposes.