What is the postal abbreviation for Pennsylvania?

The postal abbreviation for the state of Pennsylvania is PA.

In 1963 the Post Office Department published the now-familiar list of two letter state abbreviations. The implementation of two-letter state abbreviations was gradual; initially they were intended for optional use only by large business mailers in conjunction with ZIP Codes. To date, only one change has been made to the abbreviations issued in October 1963. In November 1969, at the request of the Canadian postal administration, the abbreviation for Nebraska, originally NB, was changed to NE, to avoid confusion with New Brunswick in Canada.

Pennsylvania, officially the Commonwealth of Pennsylvania, is a state located in the northeastern and Mid-Atlantic regions of the United States. It is the 33rd-largest state by area, and the 6th-most populous state according to the most recent official U.S. Census count in 2010. It is the 9th-most densely populated of the 50 states. Pennsylvania's two most populous cities are Philadelphia (1,580,863), and Pittsburgh (302,407). The state capital and its 10th largest city is Harrisburg. Pennsylvania has 140 miles (225 km) of waterfront along Lake Erie and the Delaware Estuary.