Wescosville is a census-designated place located in Lehigh County, Pennsylvania. It is located between Allentown and Trexlertown in Lower Macungie Township. It is part of 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. As of the 2010 census, the population of Wescosville was 5,872. Its ZIP Codes are split between the Allentown codes of 18103, 18104, and 18106.