Pennsylvania (Commonwealth of Pennsylvania) is in the northeastern part of the United States, with a land area of 119,000 square kilometers and a population of 12.8 million. The zip code is abbreviated as PA. Pennsylvania's government seat is Harrisburg, and other major cities include Allentown, Philadelphia, Altoona, Bethlehem, and Pittsburgh. Pennsylvania's transportation industry is quite developed, and roads and railroads are like spider webs. The sea canal has many ports, and ships can sail to the Atlantic Ocean, the Gulf of Mexico, and enter the Great Lakes through inland rivers. Famous ports are: Philadelphia, Pittsburgh, Erie. Philadelphia International Airport is the transshipment center for US Airways, and the Port of America is the third busiest shipping center in the world. The zip code for Pennsylvania is 19019 and the zip code for Philadelphia is 19113.