Rochester is a city in Strafford County, New Hampshire, United States. The population was 32,492 at the 2020 census, making it the 6th most populous city in New Hampshire. In addition to the downtown area, the city contains the villages of East Rochester, Gonic, and North Rochester. Rochester is home to Skyhaven Airport and part of Baxter Lake. Rochester was one of New Hampshire's fastest growing cities between 2010 and 2020.