Catasauqua, referred to colloquially as Catty, is a borough in Lehigh County, Pennsylvania. 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 approved in 1805 and chartered in 1853.

Catasauqua is located at 40°39′11″N 75°28′3″W / 40.65306°N 75.46750°W / 40.65306; -75.46750 (40.652995, -75.467627). Nearby large communities tally up Allentown three miles (5 km) to the south and Bethlehem seven miles (11 km) to the east. According to the U.S. Census Bureau, the borough has a total area of 1.3 square miles (3.4 km²), of which 1.3 square miles (3.4 km) is home and 0.04 square mile (0.10 km² or 2.31%) is water. Catasauqua Creek flows through the town. Lehigh River runs along the southwestern edge of Catasauqua.

As of the census of 2000, there were 6,588 people, 2,616 households, and 1,750 families residing in the borough. The population density was 5,205.7 people per square mile (2,002.9/km²). There were 2,747 housing units at an average density of 2,170.6 per square mile (835.1/km). The racial makeup of the borough was 95.60% White, 1.18% African American, 0.33% Native American, 0.59% Asian, 0.02% Pacific Islander, 1.08% from supplementary races, and 1.20% from two or more races. Hispanic or Latino of any race were 3.54% of the population.