( Health.com ) -- Fewer U.S. adults are smoking , and those who do smoke are on average smoking less , according to a new study in the Journal of the American Medical Association . Smoking rates in the U.S. have dropped dramatically over the past several decades , falling from 40 % in 1965 to about 20 % in 2006 . Much of that decline is due to a disproportionate decrease in the number of people who smoke at least a pack a day , the study found . In 1965 , 56 % of all adult smokers consumed 20 cigarettes or more per day . By 2007 , that figure had fallen to 41 % . In California , which has a history of unusually aggressive antismoking programs , the decrease was even larger : Only 23 % of all smokers smoked at least a pack a day in 2007 , according to the study , which mined data from two long-running government surveys . Health.com : 15 ways smoking ruins your looks . These declines appear to be caused by a combination of heavy smokers quitting altogether and fewer young people ramping up to a pack-a-day-habit , the researchers say . The decrease in smoking rates `` is all coming out of heavy smokers , '' says John P. Pierce , Ph.D. , the lead author of the study and the director of cancer prevention and control at the University of California San Diego 's Moores Cancer Center . `` The population [ of smokers ] is changing . '' The decline in heavy smoking appears to be linked to a subsequent decline in lung cancer . In 1993 , when the deaths caused by lung cancer peaked in the U.S. -- about 15 years after the rates of heavy smoking peaked -- 1 in every 855 deaths was attributable to the cancer . By 2007 , lung cancer was responsible for just 1 in every 980 deaths . ( These figures do not include California , which had even lower rates . ) Health.com : 6 common smoking triggers -- and how to fight them . `` We knew that lung cancer was caused almost entirely by smoking , and it 's the amount you smoke that matters , '' Pierce says . `` It was always the heavier smoker that was getting lung cancer . '' The findings are `` great news , '' says Norman Edelman , M.D. , chief medical officer of the American Lung Association . `` This shows the dramatic effect of our smoking cessation and prevention programs . This is also a victory for public health and disease prevention agencies , which are generally poorly funded in the U.S. '' The decline in heavy smoking has been especially pronounced in California , the country 's most populous state . In 1965 , 23 % of California adults smoked 20 or more cigarettes a day , whereas only 3 % smoked that heavily in 2007 . Health.com : Social , sneaky , or skinny ? The 7 types of smokers . The authors attribute the success in California to the state 's wide-ranging antismoking efforts . The state was the first to substantially raise taxes on cigarettes , the first to institute a comprehensive antismoking program , and the first to banish smoking in workplaces statewide , the study notes . In fact , the study itself is a product of the state 's antismoking efforts . The research was funded with grants from the University of California that , by law , are supported by state cigarette taxes . In addition , one of the study 's coauthors , David W. Cowling , is the chief of evaluation for the California Tobacco Control Program , a division of the state department of public health whose budget is funded with the same taxes . Despite the progress seen in the study , Edelman cautions that the fight to reduce smoking is far from over . `` Twenty percent of American adults still smoke and tobacco is still causing lots of major disease , '' he says . `` We should not use this news to declare victory , but be encouraged by the success of our actions so we can vigorously press on to reduce the use of tobacco further . '' Copyright Health Magazine 2011 .
Smoking rates in the U.S. have dropped dramatically over the past several decades . In 1965 , 56 % of smokers consumed 20 cigarettes daily . By 2007 , it had fallen to 41 % . The decline in heavy smoking appears to be linked to a decline in lung cancer .