Oscar's right, the mobs power in the Teamsters were mostly through Mid-West families, like Chicago and Detroit, being the big one and most obvious and spoken about. Size wasn't the ultimate factor, it was mostly about the connections made, Kansas City is in this group too, that's how they got connect to a president, through corrupt union men who'd made those connections, rubbing elbows with local politicians, who were then backed with union/mob money into gaining more prominent, federal positions. Gus Russo's The Outfit book goes deep into the union connections Chicago had and how they got them, as well as a whole section dedicated to Kansas City & Truman.
Most of the mobbed up Teamster presidents came from the Midwest but the question is what family had the most influence. Hoffa originated in Detroit but would have never been elected in the first place without the support of Anthony Provenzano (and Johnny Dioguardi). Frank Fitzsimmons primarily answered to Provenzano. Roy Williams was affiliated with Kansas City and Jackie Presser with Cleveland but it was Fat Tony Salerno and other Genovese leaders who ultimately selected them as Teamster presidents.
