The argument that the monopoly must be preserved in order to maintain the uniform postage rate presupposes that uniform postage is itself a desirable objective.
It was proposed in 1851 both as a result of the decrease in postage rates from five cents to three and to answer the need for a small-denomination, easy-to-handle coin.
As a depression-era measure, postage rates for private mail had increased to two pennies (this was reversed in 1932), and so a second stamp was needed.
