Carlisle is a borough in and the county seat of Cumberland County, Pennsylvania, United States. The name is locally pronounced with emphasis on the second syllable. Carlisle is located within the Cumberland Valley, a highly productive agricultural region. As of the 2010 census, the borough population was 19,262. Including suburbs in the neighboring townships, 37,695 live in the Carlisle urban cluster. Carlisle also is an exurb of Harrisburg, Pennsylvania, to the east.