The 2021 Allegheny Technologies strike was a labor strike involving about 1,300 workers for metals manufacturing company Allegheny Technologies Incorporated (ATI), all unionized with the United Steelworkers (USW). The strike began on March 30 and ended on July 13 with the ratification of a new labor contract. Strikers returned to work by July 19. According to the Northwest Labor Press, the strike was among the country's largest for 2021 by number of strikers involved.