Eagles Mere is a borough in Sullivan County, Pennsylvania, United States. The population was 151 at the 2020 census. Eagles Mere was laid out in 1877 and incorporated in 1899. The Eagles Mere Historic District was added to the National Register of Historic Places in 1996. Eagles Mere's name literally means "the eagle's lake", the word mere being a poeti…Eagles Mere is a borough in Sullivan County, Pennsylvania, United States. The population was 151 at the 2020 census. Eagles Mere was laid out in 1877 and incorporated in 1899. The Eagles Mere Historic District was added to the National Register of Historic Places in 1996. Eagles Mere's name literally means "the eagle's lake", the word mere being a poetic synonym of "lake".