Wish it was a proper academic paper with citations--kinda annoying having to track down its sources.
Don't have time at the moment, but I did grab the paper which shows that the virus could have been present in the US as early as December 13-16 2019 on the west coast:
https://academic.oup.com/cid/article/72/12/e1004/6012472
and this NIH study which also showed earlier cases than had been officially confirmed: