First COVID-19 case identified in the USA, in Snohomish County, Washington.

Source:

• 
  January 21, 2020. Audrey Mcnamara. “CDC Confirms First Case of Coronavirus in the United States.” CBS News. Runtime of embedded video: 1:51.
  https://www.cbsnews.com/news/coronavirus-centers-for-disease-control-first-case-united-states/.
  News, Video.
• 
  May 12, 2020. Susan V. Lawrence. “COVID-19 and China: A Chronology of Events (December 2019-January 2020).” R46354. Congressional Research Service.
  https://crsreports.congress.gov/product/pdf/R/R46354/1.
  Government.