(CNN) -- Smoking can kill you. We've known that for at least 50 years -- and yet millions still smoke, and thousands more pick up the habit every year.
Why? Their stories involve strong addictions, passionate defiance -- and billions spent to make people act against their own best interest.
How bad is it?
In 1965, 42% of the population smoked. Today, 19% of Americans do, according to the Centers for Disease Control and Prevention. That number sounds comparatively small, but that's an estimated 43.8 million Americans -- and the decline in smoking has plateaued, experts say.
Saturday is the 50th anniversary of the landmark U.S. Surgeon General's report that linked smoking with bad health. The government has issued yet another edition of the report, its 32nd. Barring a drastic change, experts say the government will be issuing these same reports, warning of the dangers of smoking, for many more years.
Smoking is still the No. 1 cause of preventable death in the United States, and has been for decades. It kills more people than obesity, substance abuse, infectious disease, firearms, and traffic accidents, according to the CDC. Some 443,000 Americans die from smoking-related illnesses every year, according to the U.S. Department of Health.
Even President Barack Obama, who has pushed some of the toughest anti-tobacco laws in history, admitted in 2009 that he stopped smoking but still "falls off the wagon" sometimes. The urge to smoke is that strong.
A portrait of defiance
"Smoking is my best friend," Barry Blackwell said. Blackwell perfectly embodies the predicament of how the smoking culture has changed, but his smoking hasn't. He is so closely associated with the habit he is featured in an elegant portrait series documenting smokers' lives.
"I thought it was interesting to explore why people continue to smoke in the face of public repulsion," said Laura Noel, a professional photographer and Emory University instructor who hopes to turn the series into a book.
While shooting these portraits, she noticed the age difference among smokers. Young smokers, she said, enjoy it with a kind of practiced defiance. "You see a little more of the addiction when people get older."
Blackwell is nearly 60 and runs the last black-and-white photo development studio in Atlanta.
He says he has held onto this other old-fashioned activity -- smoking -- for about as long as there have been Surgeon General warnings. When he started at age 8, however, he knew nothing about the health risks.
Blackwell is a child of tobacco country. He grew up in North Carolina. Like several generations before him, he spent summers working the family tobacco farm.
"Everyone around me smoked, everyone," Blackwell said. "Every room in the house had an ashtray. I don't remember anyone at school telling me it was bad. I even remember going to the doctor for a regular checkup and he'd examine me with a cigarette hanging out of his mouth. It was a way of life."
When he joined the Marines, the government daily gave Blackwell cigarettes with his C-rations. Over the years, though, his smoking-supportive environment changed.
Smoking despite the restrictions
His own mother quit a couple of decades ago after experiencing chest pains. "She's been after me ever since," Blackwell says. Fewer public places let him smoke. Even the park Blackwell used to exercise in went smoke-free last year.
And while he jokes he was a "pretty young thing back in the day" and "had (his) fun when it was more socially acceptable to smoke" it's harder now for him to date. "Women don't like guys who smoke," he said.
He's put restrictions on himself, keeping his smoking to one room in his "mancave." But he's not ashamed of smoking, and refuses to lie about it like the estimated 40% of traditional cigarette smokers who say they do, according to an independent research firm that conducted a recent survey on behalf of an e-cigarette company, V2 CIgs.
Still, Blackwell said he understands the reasons behind deception.
"People look at you with less regard when you smoke," Blackwell said. Strangers who see him smoke tell him it will kill him, he said. "It's one of the few socially acceptable prejudices left."
He's tried to quit, but nothing worked. In fact, in the '80s he had more success quitting a drug that is supposed to be more addictive. "Cocaine was a lot easier to kick than cigarettes," he said.
There's a very good reason for that.
'They will lose their capacity to make a free choice'
While smoking harms your health, you don't notice it at first. That's why the World Health Organization calls tobacco a "gradual killer." By the time smokers may feel the effects, they're addicted.
"Smokers typically start smoking as adolescents or young adults, with initial smoking occurring in social situations," said Sherry McKee, the director of the Yale Behavioral Pharmacology Lab. "Most young smokers believe that they can easily quit at any time and nearly all believe that they won't be long-term smokers."
"Ultimately, they will lose their capacity to make a free choice to smoke," said Jed Rose, the director of the Duke Center for Smoking Cessation in North Carolina. "Then 30 years later, that's when we typically see them in our program desperately trying to quit, because now they can't go a single day without (a cigarette)."
In addition, tobacco marketing strategies can be persuasive. Several studies show the marketing and advertising works, and increases the likelihood that youth will start smoking.
In 2011, cigarette companies spent $8.37 billion on ads and promotional expenses in the United States alone -- even with tight federal regulations on advertising, according to the CDC. That breaks down to about $23 million a day or $27 for every American per year.
Warnings on cigarette packs themselves have used increasingly stronger language over the years. In 1965, federal law required the warning "Caution: Cigarette smoking may be hazardous to your health" be placed on a side panel of the pack, according to the CDC. That changed to "Warning: Cigarette smoking is dangerous to health and may cause death from cancer and other diseases" in 1967, then "Warning: The Surgeon General has determined that cigarette smoking is dangerous to your health" in 1969.
Today's packs use one of four warnings, including "Surgeon General's warning: Smoking causes lung cancer, heart disease, emphysema and may complicate pregnancy" and "Surgeon General's warning: Quitting smoking now greatly reduces serious risks to your health."
However, warning labels in the United States are considered "weaker and less prominent" than those in other countries, according to the CDC. Some other nations use graphic images.
A U.S. move toward use of similar tactics on cigarette packs was blocked by a federal judge in 2011. U.S. District Judge Richard J. Leon cited First Amendment rights against unconstitutionally compelled speech as a factor in his decision.
Meanwhile, a strong combination of psychological and biological factors keep people smoking.
"The chemicals in cigarettes work on the structures deep within a smoker's brain, literally rewiring it so the habit becomes deeply ingrained," said Rose.
With drugs like cocaine, there can be extreme discomfort from withdrawal in those first few days, but it goes away. "The behavior addiction of smoking may be far more compelling than just the short-term withdrawal symptoms of a hard drug," he said.
That means smokers may be more addicted to the smoking behaviors than the nicotine.
"Every move a smoker makes: the lighting of the cigarette, the inhaling, all the feelings and sensations of it, the whole package becomes highly addictive," Rose said.
That's why, when helping people quit, Rose said his organization has found a patch or lozenge or drug in combination with behavioral change techniques is more successful. They're also exploring e-cigarettes as an alternative.
Jones doesn't remember why he started smoking. In fact, the 36-year-old communications consultant said he forbade his mom and grandma from smoking when they rode in the car with him.
He thinks he started to relieve stress when he moved to Washington in the mid-'90s. He tried quitting last spring, but "booze" was a trigger, he said. He can't avoid being around alcohol; on Sundays he hosts karaoke at a local bar, and says it always leaves him with an urge to smoke.
This time the patch seems to help, but it interrupts his sleep. "The patch gives me nightmares and wakes me up at 5 a.m.," Jones said.
He heads to the gym on those mornings. The exercise seems to be an adequate distraction, he said.
"I figured I'd change everything at once, my eating habits and exercise habits and smoking habits so I'll be better ready for a total change."
Blackwell, meanwhile, said he thinks he's quit trying to quit.
"I still run and am still healthy and I've got lots of smokers in my family who lived long into their late 80s," Blackwell said. "Smoking is always with me long after friends have left and people have gone. Cigarettes are always here."