Regional geological investigations of nuclear power plant sites in Wisconsin have revealed conflicting information in published references to faults. Faults reported 45 years ago had been reinterpreted by subsequent authors, causing confusion as to the existence, location, and extent of these faults. Several of the changes appear to be due to drafting errors. The diagrammatic nature of the original maps has been largely ignored by investigators. The importance of correctly presenting and verifying structural data is stressed. Four faults (Madison, Waukesha, Two Rivers, and Peshtigo-Brussels) in southern and eastern Wisconsin serve as case histories.