Local 55 is the exclusive bargaining agent for all professional firefighters, engineers, captains, battalion chiefs, code compliance officers, deputy fire marshals, dispatchers, dispatch supervisors, and PPE specialists within the Alameda County Fire Department.

Local 55 is an amalgamated union with the brothers and sisters of the Oakland Fire Department. Formed in 1918, Local 55 began with Oakland forging the strong labor community that exists today. San Leandro Firefighters, Piedmont Firefighters, and Emeryville Firefighters have all been part of Local 55.

In 1995 the City of San Leandro joined the Alameda County Fire Department and the agreement to bring the current IAFF members into Local 55 occurred.

Today, nearly 400 Alameda County employees are members of Local 55.