The first reported case came on January 21. Within 99 days, 1 million Americans became infected.
It took just 43 days after that to reach 2 million cases.
And 28 days later, the US reached 3 million cases of the novel coronavirus Wednesday.
https://www.cnn.com/2020/07/08/health/us-coronavirus-wednesday/index.html
附：
1. BBC：对逃过死亡的新冠患者来说 一切仅仅是开始
https://www.wenxuecity.com/news/2020/07/08/9640937.html
2. 约翰霍普金斯大学：
新冠数据： https://coronavirus.jhu.edu/map.html
相应数据分析：https://coronavirus.jhu.edu/testing
