McCormick Potatoes are a variety of potato that possibly no longer exists.
They were referenced in a 1946 study, so were developed before then and still extant then.
Late harvest.
Sources
C. O. Appleman and Russell G. Brown. Relation of Anaerobic to Aerobic Respiration in Some Storage Organs with Special Reference to the Pasteur Effect in Higher Plants.
Botanical Society of America: American Journal of Botany. Vol. 33, No. 3 (Mar., 1946), pp. 170-181.