Pfefer's correspondence (VII.i.) includes an estimated 5,400 individual letters and telegrams. They are almost entirely incoming, as Pfefer appears not to have made (or preserved) copies or carbons of his outgoing letters. The bulk of the material pertains to wrestling. Given the itinerant nature of the business, with performers traveling from venue to venue on a daily basis, correspondence between wrestlers and their managers or booking agents could be intensive. Letters were often accompanied by clippings showing match coverage in the local papers (as were letters between promoters). Such enclosures are included alongside their letters. Pfefer originally filed his letters in envelopes dedicated to the purpose, organized by correspondent. He also held letters in subject files (Series V.); these have been relocated to the present series.