Keith Naughton
Bloomberg News

The United Auto Workers membership rose 0.5 percent to 382,513 last year, the unionís highest since 2008 and the third consecutive gain, as U.S. automakers added employees amid rising sales.

The UAW disclosed the 2012 figure, the largest for the union since its membership totaled 431,037 in 2008, in an emailed statement that cited a union filing with the U.S. Labor Department. The union added 1,794 members from 380,719 in 2011.

General Motors, Ford and Chrysler gained sales in the U.S. last year when combined they earned $13.5 billion. While the UAWís 2012 gain followed a 1.1 percent increase in 2011, the UAWís total membership is still only about one-fourth its size in 1979, when it peaked at 1.5 million members.

The UAW, based in Detroit, is seeking to rebuild membership by trying to organize workers at the U.S. factories of Volkswagen and Nissan. The UAW previously failed to convince workers to join the union at Nissan as well as the U.S. factories of Toyota and Honda.

UAW President Bob King has said the unionís future depends on expanding membership by organizing workers at the U.S. factories of European and Asian automakers. He failed in a pledge to organize one of those plants in 2011.

Volkswagen has said itís in exploratory talks concerning possible labor union representation at a Chattanooga, Tenn., factory.