Below is a list of Williamstown PA zip codes. For your research we have also included Williamstown Area Code, Time Zone, UTC and the local Dauphin County FIPS Code. Each Williamstown Pennsylvania zip code has a center Longitude / Latitude point (the Williamstown center is -76.615898132324 / 40.580699920654). For your convenience we have also indicated if that zip code in Williamstown observes Daylight Savings time.