Nada

It's been a concern that perhaps the virus was in the U.S. prior to January.

This isn't definitive, but Stanford took every preserved nasal swab they had (almost 2K or them) from November and December, and tested them. They got zero positives.

The University of Washington also did this, but for all 3K + samples from the months of January and February. They found nothing prior to February 21st.