In a landmark victory for organized labor, workers at a Volkswagen plant in Tennessee have voted overwhelmingly to join the United Automobile Workers union, becoming the first nonunion auto plant in a Southern state to do so.

The company said in a statement late Friday that the union had won 2,628 votes, with 985 opposed, in a three-day election. Two earlier bids by the U.A.W. to organize the Chattanooga factory over the last 10 years were narrowly defeated.

The outcome is a breakthrough for the labor movement in a region where anti-union sentiment has been strong for decades. And it comes six months after the U.A.W. won record wage gains and improved benefits in negotiations with the Detroit automakers.

The U.A.W. has for more than 80 years represented workers employed by General Motors, Ford Motor and Stellantis, the producer of Chrysler, Jeep, Ram and Dodge vehicles, and has organized some heavy-truck and bus factories in the South.

But the union had failed in previous attempts to organize any of the two dozen automobile factories owned by other companies across an area stretching from South Carolina to Texas and as far north as Ohio and Indiana.

With the victory in Chattanooga, the U.A.W. will turn its focus to other Southern plants. A vote will take place in mid-May at a Mercedes-Benz plant in Vance, Ala., near Tuscaloosa. The U.A.W. is hoping to organize a half-dozen or more plants over the next two years.