At a time when the U.A.W. has fewer than one-third of the 1.5 million workers it had in 1979, its organizing push in the South has taken on urgency and is being watched closely by labor leaders across the country.
"It's a life-and-death matter for the U.A.W. to succeed in the South," said Nelson Lichtenstein, a professor and labor historian at the University of California, Santa Barbara. "That's why they've put their best organizers into this campaign."
The unionization battle has badly divided workers at the gleaming white Nissan plant here, which stretches four-fifths of a mile along Interstate 55 and produces 450,000 Altimas, Sentras and other vehicles a year. The pro-union forces say many workers are backing the U.A.W., while anti-union workers insist the union has little chance of gaining majority backing. Some anti-union workers wear T-shirts saying, "If you want a union, move to Detroit."
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Despite the union's previous failures in the South, Bob King, the U.A.W.'s president, has undertaken its most ambitious campaign in the region. In addition to Canton, it is also pushing to organize Volkswagen's plant in Chattanooga, Tenn., and the Mercedes-Benz plant in Vance, Ala.
"Bob King has basically staked his legacy on organizing these international assembly plants," said Kristin Dziczek, director of the labor and industry group at the Center for Automotive Research. "Unless they unionize more of the automotive work force in the country, they will become wage takers, not wage setters."
If the U.A.W. fails to win at the foreign companies' plants in the South, Ms. Dziczek said, they will pull down wages at General Motors, Ford and Chrysler.
The union faces rough going in Mississippi, she said, considering the embarrassing loss it suffered in 2001 when workers at Nissan's plant in Smyrna, Tenn., voted two to one against joining the U.A.W.
Mr. King vows better results this time. "What's different this time is there is really strong and active community support," he said. Noting that unions in Japan, Germany, Australia and Britain are backing the Mississippi fight, he added: "That kind of global pressure on them, as a labor rights violator, will make a big difference. There are outrageous violations of the workers' right to organize."
Union officials say they have not filed any complaints with the National Labor Relations Board but might do so. Ricardo Patah, president of Brazil's gigantic General Workers Union—it has 7 million members and has pledged to picket dozens of Nissan dealerships—said in an interview, "We're not going to stop until they have a union inside the plant in Mississippi."
The unionization drive has certainly raised tensions in Canton. On the picturesque town square, with its handsome, pre-Civil War courthouse, Sheaford Davidson, who helps run a company that makes cemetery headstones, said, "We're a right-to-work state." He added, "Back in the Industrial Revolution I could see why unions were needed, but we're now in 2013, and I don't see the need."
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For Mississippi, landing Nissan was a coup. The 10-year-old auto plant was the state's first, and its work force has climbed to 5,200, making Nissan the state's second-largest private employer behind Ingalls Shipbuilding. Blake Wilson, president of the Mississippi Economic Council, the state's chamber of commerce, praises Nissan for bringing thousands of jobs and donating millions to charities and the Canton school system.
"Across the South, the spirit of a nonunion environment has been a positive in the growth of all kinds of manufacturing," Mr. Wilson said. "The nonunion environment has been a market edge in Southern states. But if you start seeing that change, it will certainly be a loss for the region."
Nissan has invested $2 billion in its state-of-the-art plant, which uses 1,200 robots. The base wage for most of the plant's workers is $23.22 an hour, making them the envy of many blue-collar workers in Mississippi.
Nonetheless, Morris Mock, a muscular paint technician, strongly backs unionization.
"We're grateful that Nissan came to Mississippi, but as I grow older, I see that there are safety issues and ergonomic issues that need to be addressed," said Mr. Mock, 39, who has worked at the plant since it opened. "Nissan started out one way, then things changed. We want to make sure our voices are heard."
Many pro-union workers complain that the company does not listen to workers as much as they would like and puts injured workers back on the line too soon. Many are upset that their wages were frozen for five years and that the plant has hired hundreds of temporary workers, many of them starting around $12 an hour. Many experienced workers complain that they are relegated to night shifts because the temporary workers are often given the coveted day shifts.
"They give them the easier jobs so they won't leave," said Chip Wells, also a paint technician. "They're standing next to us doing the same job, receiving less benefits and less pay. That's not fair."
Union officials estimate that 40 percent of the plant's production workers are temporary. They would not be eligible to participate in the U.A.W. unionization vote. Company officials declined to disclose the number.
Claude Potter, 37, a repair technician in trim and chassis, left his job as an automobile salesman to work at Nissan 10 years ago, convinced that the pay would be steadier.
"I don't think we should have a union," Mr. Potter said. "I don't need to pay somebody to talk for me. If I have a problem, I can go to whoever I need to go to. Is this place perfect? No, but I never worked nowhere where it ever was perfect."
Camille Young, Nissan's community relations manager in Canton, noted that most of the plant's workers were to receive a raise of 55 cents an hour this month. As for complaints about the wage freeze, Nissan officials pointed out that Detroit's automakers also had an extended freeze, and added that the Canton plant did not lay off anyone during the recession.
The battle's most emotionally freighted issue involves accusations by some pro-union workers that Nissan managers have sought to intimidate them.
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"They say the Big Three shut all these plants down because they were union, and they say if we get a union, they'll shut our plant down," said Betty Jones, who attaches parts to vehicle engines. "A lot of people who want the union feel that if they're open about it, they're going to lose their jobs."
Justin Saia, a Nissan spokesman, denied that managers had made such threats. "Nissan is a company that doesn't tolerate intimidation of employees," he said. "That wouldn't be tolerated as a part of our culture."
These tensions are a far cry from what is happening at Volkswagen's Chattanooga plant. The U.A.W.'s regional director said last month that the majority of the plant's 2,000 workers had already signed cards backing unionization.
Moreover, Volkswagen—under pressure from the mighty IG Metall union in Germany—has said it would cooperate with the U.A.W. to form a works council in Chattanooga. Such councils, common in Germany, include blue-collar and white-collar employees and work with management to increase productivity and administer factory rules.
U.A.W. leaders acknowledge that under American law, the Volkswagen plant would need to be unionized first. Some U.A.W. officials are urging Volkswagen to recognize the union based on a majority of cards they say have been signed. But corporate-backed groups like the Workplace Fairness Institute favor an election with secret ballots.
"There's a lot of pressure on VW to recognize the union," said Lowell Turner, a professor of international labor relations at Cornell. "Something like 61 out of its 62 plants worldwide have unions and works councils. The only one that doesn't is Chattanooga."
Recognizing that it faces a steeper climb in Mississippi, the U.A.W. has made an unusual demand. The union wants Nissan to agree to what it calls "fair election principles" that would allow its organizers equal time on company ground—to counter what the union says have been numerous anti-union meetings and videos. Mr. King said the union would not officially seek a vote until Nissan agreed to these principles.
Like many of her co-workers, Ms. Jones voices dismay that Canton's workers are generally paid $2 less an hour than Nissan's workers in Smyrna. The company says that workers at the Tennessee plant, which is 30 years old, have more experience.
Explaining why she favors a union, she said: "I can, of course, talk to you all day long, but if I'm not at the table with you, when you're making a decision about safety, my health care, my salary, I don't have any impact on my situation. But if I have 100,000 people behind me at the table, that will make a difference."
Nissan officials say the company already complies with all legal requirements on unionization efforts.
"Nissan has been committed to following the letter of the law of the N.L.R.B.'s requirements," said Ms. Young, the community relations manager. "Nissan greatly respects the right of our employees to choose who represents them."
But union officials warn that they will escalate their fight if they are not given equal access with Nissan. "The auto companies are very concerned about their brand image," Mr. King said. "When we have these union partners all over the world, and they see you violating basic worker rights in the U.S., that hurts your relationships in all those places, and it hurts your brand image."
Still, Stephanie Sutton, a paint technician for 10 years, insists that the union has less support than it realizes. She said many workers were speaking out for a union to pressure Nissan to give larger raises, but would not vote for the U.A.W.
"You have a lot of people who talk the talk, but I don't know if they're going to stand up when it counts," she said.
—By Steven Greenhouse for The New York Times