Allentown (Pennsylvania Dutch: Allenschteddel) is a city located in Lehigh County, Pennsylvania, United States. It is Pennsylvania's third most populous city and the 233rd largest city in the United States. As of the 2010 census, the city had a total population of 118,032 and it is currently the fastest growing major city in Pennsylvania with an estimated 121,442 residents according to the 2019 census estimate. 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 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 approximately 60 miles (97 km) north-northwest of Philadelphia, the sixth most populous city in the United States, 60 miles (97 km) south-southeast of Scranton and the Wyoming Valley, 80 miles (130 km) east-northeast of Harrisburg, the state capital, and 75 miles (121 km) west of New York City, the nation's largest city. Being centrally located in the Northeast Megalopolis, there are approximately 30 million people living within 100 miles (160 km) of Allentown and the city has direct access to some of the largest markets, seaports, airports, railways and population centers in the United States but with a lower cost of living than many surrounding cities and regions.
Allentown was one of only six communities in the country to have been named a "national success story" in April 2016 by the Urban Land Institute for its downtown redevelopment and transformation that has generated nearly $1 billion in new development projects as of April 2019.
In the early 1700s, the land now occupied by the city of Allentown and Lehigh County was a wilderness of scrub oak where neighboring tribes of Native Americans fished for trout and hunted for deer, grouse, and other game. In 1736, a large area to the north of Philadelphia, embracing the present site of Allentown and what is now Lehigh County, was deeded by 23 chiefs of the five great Native American nations to John, Thomas, and Richard Penn, sons of William Penn. The price for this tract included shoes and buckles, hats, shirts, knives, scissors, combs, needles, looking glasses, rum, and pipes.
The land that was to become Allentown was part of a 5,000-acre (20 km2) plot William Allen purchased on September 10, 1735, from his business partner Joseph Turner, who was assigned the warrant to the land by Thomas Penn, son of William Penn, on May 18, 1732.
The land was originally surveyed on November 23, 1736.