Unadilla was platted in 1871 along the Midland Pacific Railway, which entered the state at Nebraska City and continued west through Unadilla and points beyond. As of 2016, the population of this quaint town was 322 and has grown 3.5% since the 2010 US Census. The Unadilla Main Street Historic District is listed in the National Register of Historic Places.
Unadilla has been designated as the Groundhog Capital of Nebraska. The Unadilla Groundhog Day is traditionally celebrated the first weekend of February with a 2-block parade that usually lasts for at least 45 minutes, silent auction, soup contest, kid’s activities, craft show, flea market and a re-enactment of a historical character, sponsored by Nebraska Humanities. On the 4th Saturday of June, Unadilla Day is celebrated. A 5K Run/Walk, City-wide Garage Sales, Water Slide, Sand Volleyball and Horseshoe Tournaments and a BBQ meal are some of the events for the day.