The 2018 Farm Bill (pdf) directed USDA to establish a national regulatory framework for hemp production in the United States.
USDA published a final rule on January 19, 2021, that provides regulations for the production of hemp in the United States and is effective on March 22, 2021. The final rule builds on the interim final rule published October 31, 2019, that established the U.S. Domestic Hemp Production Program. The final rule incorporates modifications based on public comments and lessons learned during the 2020 growing season.
The Code of Federal Regulations (CFR) for the U.S. Domestic Hemp Production program can be found at this link.
https://www.ecfr.gov/current/title-7/subtitle-B/chapter-IX/part-990