In the larger populated cities of the time, merchants found a way to cater to busy customers who had little time or energy to prepare food during the evening. The variation in Chinese cuisine from different regions led caterers to create a list or menu for their patrons.
ZIP Code began on July 1, 1963, as scheduled. Use of the new code was not mandatory at first for anyone, but, in 1967, the Post Office required mailers of second- and third-class bulk mail to presort by ZIP Code. Although the public and mailers alike adapted well to its use, it was not enough.
Modern two-letter abbreviated codes for the states and territories originated when the Post Office introduced ZIP codes in 1963. The purpose was to make room for ZIP codes in the address, rather than to standardize state abbreviations per se. Since 1963, only one state abbreviation has changed.