Building structures made from logs appeared in the eastern United States during the late 17th century, and immigrants from Sweden, Finland, and Germany are credited with their construction. There were two types of structures: the horizontal design introduced by the Scandinavians and the German or Pennsylvania Dutch model that was used by the westward pioneers. Since the principal construction material was logs, these structures ceased to be built after westward-moving pioneers reached the prairie regions. The most distinctive feature of a log building was its corner-timbering or notching, and the full and half dovetail, square, saddle or round, and the V-notch are described and accompanied by hand-drawn illustrations. The concluding portion of the document contains black and white photographs and the specifications for 20 log structures located around St. Peter, Minnesota. A map showing this area and the 20 building locations and a map of the distribution of log buildings in the eastern United States are provided. Eleven references are also included. (DJC)