sentences:  This allowed Piatt County to tax utility assets over half of the state, providing a rich source of revenue which was responsible for much of the wealth of this tiny county.According to the US Census Bureau, the county has a total area of , of which is land and (0.06%) is water.In recent years, average temperatures in the county seat of Monticello have ranged from a low of in January to a high of in July, although a record low of was recorded in January 1999 and a record high of was recorded in July 1966.