UAW tests Southern expansion at two Alabama Mercedes plants in key vote

If the union wins, it will be a huge momentum booster for the UAW as it seeks to organize more factories.

The United Auto Workers union faces the latest test of its ambitious plan to unionize auto plants in the historically nonunion South when a vote ends Friday at two Mercedes-Benz factories near Tuscaloosa, Alabama.

The voting at the two Mercedes factories — one an assembly plant, the other a battery-making facility — comes a month after the UAW scored a breakthrough victory at Volkswagen’s assembly factory in Chattanooga...