U.S. state and territory abbreviations

Who came up with U.S. state abbreviations? We can largely thank the U.S. Postal Service (USPS), which has created abbreviations during much of its history. In 1831 the USPS developed its first list of state abbreviations, each consisting of two letters except Ohio’s, which was simply “O.” In 1874 the list was updated to include new states, and longer abbreviations were introduced, largely to avoid confusion. The next significant change occurred in 1963 when the Post Office went back to two-letter abbreviations. Why? Because ZIP codes were adopted that year, and, owing to the limitations of addressing equipment, abbreviations had to be shortened to make room for the numbers. While the two-letter abbreviations are now preferred, the earlier versions continue to be widely used. In the table below, we provide abbreviations for each U.S. state and territory.