Penn Yan is an incorporated village and the county seat of Yates County, New York, United States. The population was 5,159 at the 2010 census. It lies at the north end of the east branch of Keuka Lake, one of the Finger Lakes. Penn Yan, New York is home to one of the oldest mills in the United States, The Birkett Mills, founded in 1797. The Village of Penn Yan is primarily in the Town of Milo, but a small section is in the Town of Benton. A smaller section is in the Town of Jerusalem.