Below is a list of Dennison IL zip codes. For your research we have also included Dennison Area Code, Time Zone, UTC and the local Clark County FIPS Code. Each Dennison Illinois zip code has a center Longitude / Latitude point (the Dennison center is -87.597999572754 / 39.46070098877). For your convenience we have also indicated if that zip code in Dennison observes Daylight Savings time.