Using panel data on union locals in the United States we examine the dynamics of the union sector, investigating the impact of inter‐union competition on locals' productivity and survival. We find low entry rates, high exit rates and high levels of productivity dispersion in the sector. The entry of new locals is not associated with productivity improvements among incumbents but has a small negative association with locals' survival rates. These findings indicate that inter‐union competition is not effective in raising productivity and the effects of creative destruction are weak, with these processes likely insufficient to stem the sector's overall decline.