American Maritime Officers (AMO) is a national labor union affiliated with the Seafarers International Union of North America. With an active membership of approximately 4,000, AMO represents licensed mariners working in the United States Merchant Marine aboard U.S.-flagged merchant and military sealift vessels. AMO holds a unique presence in the international energy transportation trades.

The Seafarers International Union or SIU is an organization of 12 autonomous labor unions of mariners, fishermen and boatmen working aboard vessels flagged in the United States or Canada. Michael Sacco was its president from 1988 until 2023. The organization has an estimated 35,498 members and is the largest maritime labor organization in the United States. Organizers founded the union on October 14, 1938. The Seafarers International Union arose from a charter issued to the Sailors Union of the Pacific by the American Federation of Labor as a foil against loss of jobs to the Congress of Industrial Organizations (CIO) and its Communist Party-aligned faction.