Very-High-Denomination Treasuries
For most of their history after World War II, Treasury notes were issued with denominations never rising above a high of $1 million. Yet, from 1955 to 1969, the Treasury issued Treasury notes with the added denominations of $100 million and $500 million. Why did the Treasury issue these very-high-denomination Treasury notes and why did it stop doing so?
Very-high-denomination Treasury notes arose from the Treasury’s need to use Treasury notes as the primary vehicle for refunding the public debt. Treasury notes became the primary method of refunding the public debt because they were the only viable way, at the same time, to lengthen and consolidate the debt, as the government securities market did not support the marketing of long-term Treasury bonds. With the vast increase in the number of notes sold came increasing administrative costs both for investors and the Treasury. Keeping, tracking, and servicing billions of dollars of Treasury notes quickly became burdensome in the early 1950s. The costs and administrative difficulties were reduced by the issue of very-high-denomination Treasury notes in fiscal year 1955. A further reduction in servicing costs was made possible with the introduction of book-entry procedures in early 1968. Electronic record keeping ended the need for the very-high-denomination Treasury notes, and they were no longer offered for sale.
The image shows a modified replica of the head of an actual note. Source.