Illinois Power Company was a major electric utility in Central Illinois, centered in Decatur, to the west of Piatt County. At one time, Illinois had a "personal property tax", an ad valorem tax levied by the counties on property that was not real estate. The personal property tax was a major expense for the electric utilities, since their generators and transmission lines were "personal property". Under Illinois law, a corporation, such as Illinois Power, paid personal property tax to the county in which the corporate headquarters was located. Because Piatt County offered a low tax rate, Illinois Power moved its corporate headquarters to that county. 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.