Catasauqua, referred to colloquially as Catty, is a borough in Lehigh County, Pennsylvania, United States. Catasauqua's population was 6,518 at the 2020 census. It is a suburb of Allentown in the Lehigh Valley, which had a population of 861,899 and was the 68th-most populous metropolitan area in the U.S. as of the 2020 census. In 1839, Catasauqua was the location of the first manufactured anthracite iron in the nation. The borough was settled in 1805 and chartered in 1853.