Allentown (Pennsylvania Dutch: Allenschteddel) is a city located in Lehigh County, Pennsylvania, United States. It is Pennsylvania's third most populous city and the 231st largest city in the United States. As of the 2010 census, the city had a total population of 118,032 and is currently the fastest growing city in all of Pennsylvania. It is the largest city in the metropolitan area known as the Lehigh Valley, which had a population of 821,623 residents as of 2010. Allentown constitutes a portion of the New York City Combined Statistical Area and is the county seat of Lehigh County. In 2012, the city celebrated the 250th anniversary of its founding in 1762.
Located on the Lehigh River, Allentown is the largest of three adjacent cities, in Northampton and Lehigh counties, that make up a region of eastern Pennsylvania known as the Lehigh Valley, the other two cities being Bethlehem, Pennsylvania and Easton, Pennsylvania. Allentown is 50 miles (80 km) north-northwest of Philadelphia, the sixth most populous city in the United States, 90 miles (140 km) east-northeast of Harrisburg, the state capital, and 90 miles (140 km) west of New York City, the nation's largest city.
The Norfolk Southern Railway's Lehigh Line (formerly the main line of the Lehigh Valley Railroad using former Lehigh and Susquehanna Railroad main line trackage), runs through Allentown heading east across the Delaware River. The Norfolk Southern Railway's Reading Line runs through Allentown heading west to Reading, Pennsylvania.
Allentown was cited as a "national success story" in April 2016 by the Urban Land Institute for its downtown redevelopment and transformation, one of only six communities in the country to have been named as such.