- Your Ad Here Cortland County is a county located in the U.S. state of New York. In 2016 the estimated population was 48,070. The county seat is Cortland. Sponsored Links History Cortland County was formed in 1808. Named after Pierre Van Cortlandt, president of the convention at Kingston that wrote the first New York State Constitution in 1777, and first lieutenant governor of the state. The Cortland apple is named for the county. |