Some 440,000 Americans die of smoking-related illnesses each year
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.
About one in five Americans smoke and some 440,000 die each year of smoking-related illnesses.
US TOBACCO MILESTONES
1964: Surgeon general's report alerts many Americans to the health risks of smoking - and its links to lung cancer - for the first time
1971: Tobacco advertising banned on TV and radio
1988: Surgeon general reports nicotine is an addictive drug
1988: Smoking banned on US domestic flights under two hours; later extended but only applied to all domestic flights in 1998
1990s: FDA tries to regulate nicotine as a drug, but Supreme Court strikes this effort down in 2000, saying it requires congressional backing
2009: FDA gets strong powers to regulate the content and marketing of tobacco products
Mr Obama said in the White House Rose Garden: "When I ran for president, I did so because I believed that... it was possible for us to bring change to Washington."
He added: "Today, despite decades of lobbying and advertising by the tobacco industry, we passed a law to help protect the next generation of Americans from growing up with a deadly habit that so many of our generation have lived with."
Tougher regulation was stiffly opposed by the industry and tobacco's political backers.
Before now, tobacco was more lightly regulated than cosmetics or pet food, and previous attempts at FDA regulation were struck down by the Supreme Court as requiring congressional approval.
The law empowers the FDA to:
- Limit nicotine levels - though not banning nicotine or cigarettes entirely
- Attempt to limit the appeal of smoking among young people by limiting the use of flavours, restricting advertising in publications targeting young people, and banning outdoor tobacco advertising within 1,000 feet (300m) of schools
- Require tobacco companies to get FDA approval for new products
- Bar terms such as "light" or "mild" in tobacco packaging which imply a smaller risk to health, and introduce graphic new health warnings of packets
The Congressional Budget Office has estimated that FDA regulation could reduce underage smoking by 11% over the next decade, and adult smoking by 2%.
Paying for the new regulation is likely to end up adding to the cost of cigarettes.