At 14, Rankin dropped out of secondary school to work in a bakery and through the trade union he got involved in politics.
After the war he completed his secondary education and pursued undergraduate studies at the University of British Columbia, where he also earned a law degree.
In 1950 he was one of the founding members of a committee that created a list of lawyers who were willing to take on cases, mostly pro bono, preceding the establishment of the BC Legal Aid Society by 20 years.
Rankin helped form the Committee of Progressive Electors (COPE) as a left wing civic political party and it subsequently pushed for a ward-based electoral system to be introduced in Vancouver, culminating in a referendum in October 1973, at which the ward proposal was defeated.
He returned to city council as an alderman in the subsequent election and remained on the body until his retirement from politics in 1993.