US President Barack Obama has signed into law America's strongest anti-smoking measure ever, saying it will save lives.
The US Food and Drug Administration now has new powers to regulate the content and marketing of tobacco products.
Hailed as a milestone in the history of tobacco regulation, the bill was passed by Congress earlier this month.
The BBC reports about one in five Americans smoke and some 440,000 die each year of smoking-related illnesses.
The Congressional Budget Office has estimated that FDA regulation could reduce underage smoking by 11% over the next decade, and adult smoking by 2%.
Tougher regulation was opposed by the industry and tobacco's political backers.
Previous attempts at FDA regulation were struck down by the Supreme Court as requiring congressional approval.