Clymer is a borough in Indiana County, Pennsylvania, United States. The population was 1,336 at the 2020 census. The community was named after William Bingham Clymer, grandson of George Clymer, one of the signers of the United States Declaration of Independence. William Clymer sold the land the borough is situated on to Thomas White in the 1830s. Most of Clymer's family died in a tragic sea accident in 1878, which made national news and inspired the name.