Over 5,000 auto workers at the Mercedes-Benz assembly plant in Vance, Alabama, have been holding their union election vote with the United Auto Workers (UAW); ballots will be counted when voting closes today.

It’s the UAW’s second election in their campaign to organize non-union auto workers, with a particular focus on the South — a notoriously difficult region for union drives. They won their first election with Volkswagen workers last month in Tennessee with 73 percent of workers voting to form a union.

What makes the UAW’s recent success compelling is that they’re finding big wins at a time when union membership rates in America are at an all-time low.