SIU's roots, however, reach back to 1892, when delegates representing unions of the West Coast, the Gulf of Mexico, and the Great Lakes gathered at a seamen’s convention in Chicago.

The AFL's action to form the SIU not only countered the threat of loss of seafaring jobs to the NMU but also served as a political block against the increasing Communist influence in the rival Congress of Industrial Organizations.

[8] This consolidation helped the SIU edge out the NMU whose earlier purging of Communist Party members or those suspected of CP association had left it weakened.

At his death, Maritime Trades Department comprised 43 national and international unions representing nearly 8 million American workers.

In 1967, Hall established the Seafarers Harry Lundeberg School of Seamanship in Piney Point, Maryland, to give young people the chance for a career at sea.

Moreover, the Harry Lundeberg School has also presented opportunities for generations of young people from deprived backgrounds to gain employment.

[10] In 2005, SIU and the Paul Hall Center for Maritime Training and Education were sued for age discrimination by the Equal Employment Opportunity Commission.

In the opinion on the Fourth Circuit Court of Appeals, "throughout this appeal, and in the proceedings before the district court, the center and the union ... maintained that age-barriers to entry are a hallmark of apprenticeships and complained that the EEOC's regulation effectively guts that employment practice by erasing its defining characteristic.

"[11] In 2006 the case remanded back to the Baltimore federal district court and that court ruled in favor of the EEOC and ordered back payments in the range of $2 million to over 180 plaintiffs and further ordered that they and all future applicants to the Paul Hall maritime school be admitted regardless of age.

In testimony before the Parliament of Canada in 1996, David Broadfoot of the Canadian Merchant Navy Association recalled that in 1946, "Our government imported a thug, a real heavy-duty gangster from Brooklyn (Hal C. Banks), to smash our union and bring in the Seafarers' International Union ... which was no different from the Teamsters at its worst and no different from the longshoremen's association at its best.