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.
The ZIP Code program expanded the code to 5 digits and extended it nationwide. Implemented by the U.S. Post Office Department in 1963, the ZIP Code uses a 5-digit code to identify the individual community post offices or, in large urban areas with multiple post offices, delivery stations in metropolitan areas associated with a given address.