By the early 1960s a more organized system was needed, and on July 1, 1963, non-mandatory five-digit ZIP Codes were introduced nationwide. Three months later, on October 1, 1963, the U. S. Department of the Post Office issued its Publication 59: Abbreviations for Use with ZIP Code, with the list of two-letter state abbreviations, which are generally written with both letters capitalized. An earlier list in June had proposed capitalized abbreviations ranging from two to five letters. According to Publication 59, the two-letter standard was "based on a maximum 23-position line, because this has been found to be the most universally acceptable line capacity basis for major addressing systems", which would be exceeded by a long city name combined with a multi-letter state abbreviation, such as "Sacramento, Calif. " along with the ZIP Code. The abbreviations have remained unchanged, with the exception that in 1969, at the request of the Canadian postal administration, the abbreviation for Nebraska was changed from NB to NE to avoid confusion with the Canadian province of New Brunswick.