UAW's due-paying membership now stands at 391,415, compared to 382,513 in 2012. The UAW's hit a low of 355,191 in 2009, the year when both General Motors and Chrysler filed for bankruptcy.
The Detroit Three may have mostly recovered from the industry's nadir five years ago, but the UAW still faces many challenges. The UAW had roughly 1.5 million members in 1979 at its peak.
Annual dues collected by the UAW, the union's main source of income, have fallen more than 40 percent from 2006 to 2013. However, the drop appears to have stabilized this year, as total dues in 2013 were $115.1 million, up slightly from $115 million in 2012.
The union also failed in February to rally enough worker support to organize Volkswagen's factory in Chattanooga, Tenn., even with the passive support of VW management. The VW plant was considered a major test for the union to push its membership into the South, where several domestic and foreign automakers have been opening up factories.
To bolster its ranks, the UAW has been increasingly pushing to organize workers in non-automotive industries. The UAW said it organized casinos in Ohio and Las Vegas and was able to organize the graduate student employees of New York University.