New Federal Law - 21 year minimum-age
The new law is effective immediately.
From the FDA:
"On December 20, 2019, the President signed legislation to amend the Federal Food, Drug, and Cosmetic Act, and raise the federal minimum age of sale of tobacco products from 18 to 21 years. It is now illegal for a retailer to sell any tobacco product - including cigarettes, cigars, and e-cigarettes - to anyone under 21. FDA will provide additional details on this issue as they become available."
Source: FDA's Website