Below is a list of Seneca IL zip codes. For your research we have also included Seneca Area Code, Time Zone, UTC and the local La Salle County FIPS Code. Each Seneca Illinois zip code has a center Longitude / Latitude point (the Seneca center is -88.609397888184 / 41.303901672363). For your convenience we have also indicated if that zip code in Seneca observes Daylight Savings time.