The 1960s were a tumultuous, but crucial period in the development of professional soccer in the United States and Canada - with teams from Scotland, of all places, playing a particularly interesting role.

The dividing line for the modern North American pro game, of course, was the breakthrough, near-live (two-hour-delayed) NBC-TV network telecast of the 1966 World Cup final between eventual champion England and West Germany - the first-ever national standalone broadcast of the sport.

Prior to that watershed, it was sports entrepreneur Bill Cox's International Soccer League that imported full major European & South American teams to play in a senior-level competition in largely East Coast urban centers and first-generation immigrant communities. Among the ISL's regulars were three Scottish sides - including Kilmarnock FC, which played four seasons and made the 1960 final.

Immediately after the World Cup, no fewer than three groups of eager sports owners sought to launch a full-fledged domestic North American league; by 1967, two competing circuits bowed - including a hastily-assembled United Soccer Association, featuring full-team ISL-like imports - but under noms de plume of North American cities.  Front and center were Scottish stalwarts Aberdeen FC - masquerading as the District of Columbia's "Washington Whips."

UK football writer Mark Poole ("99 Iconic Moments in Scottish Football: From the Famous to the Obscure, Scotland’s Glorious, Unusual and Cult Games, Players and Events") tells us the stories behind these two curious Scottish contributions to US pro soccer history.

99 Iconic Moments in Scottish Football: From the Famous to the Obscure, Scotland’s Glorious, Unusual and Cult Games, Players and Events - buy book here