In October 1963, the United States Postal Service published an updated list of two-letter state abbreviations, 49 of which have stayed the same ever since. Nebraska is the sole exception, changing from NB to NE in 1969. State postal abbreviations originated in 1831, when there were 28 states and regions in the U.S. The initial abbreviations included “O.” for Ohio and “Mic. T.” for the Territory of Michigan, among others. As new states were admitted, the USPS updated the list in 1874, 1943, and finally 1963.
The 1963 list updated previous abbreviations that ranged from two to five letters long (including NEB for Nebraska), adopting universal two-letter abbreviations nationwide. However, six years later, the Canada Post unveiled an abbreviation list of its own, which shortened the province of New Brunswick to NB. The Canada Post asked the U.S. Postal Service to change Nebraska’s abbreviation in order to avoid any confusion when sending mail across North America. The request was met without resistance, and the abbreviation for Nebraska was changed from NB to NE in November 1969.