The Gas and Diesel Sternwheel Vessel Directory is intended to be a resource book comprised of all sternwheel vessels that employed gasoline or diesel engines. The Directory will list known facts about "oil-engine" sternwheelers, including sternwheel towboats, packets, ferryboats and passenger vessels.

The Directory will list all such vessels that were built for inland river commercial service. The general era for these vessels will range from 1890 to 1954, inclusive. Vessels built after 1954 will be included, but will be subcategorized as "contemporary" sternwheelers.