Lynn Township is a township in Lehigh County, Pennsylvania. It is the largest township by area in Lehigh County and also the most rural and least densely populated township in the county. The population of Lynn Township was 4,229 at the 2010 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.