It was not only in design and commemorative purpose that this issue proved a watershed in U. S. stamp history. The Columbians, like all previous U. S. stamps, had been produced by private security printers on limited-term contracts periodically presented for bidding. They proved, however, to be the last U. S. stamps printed by a private company for many years. For during early 1894, the American Bank Note Company failed to secure a renewal of its stamp contract because the U. S. Bureau of Engraving and Printing submitted a lower bid; and the Bureau then enjoyed a monopoly on U. S. stamp production for decades thereafter. Not until 1944 would a private company again produce U. S. stamps (the Overrun Countries series, which required special multicolor printing) and the Bureau subsequently resumed its exclusive role in production, only gradually relinquishing it over the next sixty years (U. S. stamp operations at the Bureau ceased entirely during 2005). Scholars believe that the Bureau's first task during 1894 was to finish some Columbian sheets printed by American Banknote; what makes this theory plausible is that, while many Columbian stamps are perfectly perforated, others are distinctly substandard in this regard, with partially punched chads and/or holes that are missing, ragged or misplaced-- flaws that would also mar the stamps of the first Bureau definitive issue, released later during 1894.