Wescosville is a census-designated place located in Lehigh County, Pennsylvania, United States. The town is located between Allentown, Pennsylvania and Trexlertown, Pennsylvania in Lower Macungie Township. It is split between the Allentown zip codes of 18103, 18104, and 18106. As of the 2010 census the population was 5,872 residents. The primary business district of Wescosville runs along Hamilton Boulevard and is bisected by the Pennsylvania Turnpike Northeast Extension (I-476). Hamilton Boulevard was part of U.S. Route 222 until the Trexlertown-Wescosville Bypass was opened in 2007.