sentences:  In past years, non-denominated postage issued by the United States differed from the issues of other countries, in that the stamps retained their original monetary value.Some stamps, such as those intended for local or bulk mail rate, were issued without denomination.This practice began in 1975, when there was uncertainty as to the timing and extent of a rate increase from ten cents for the first ounce of first class postage as the end of the year approached.