Technical Abstract: Caloric analysis of the distribution of energy were carried out for 10 cotton (Gossypium hirsutum L.) cultivars, each planted in 1999, that had been widely grown at one time during a period from 1890 to 1998. For these analyses, plants were harvested, dried, weighed, and subsequently analyzed for protein, crude fat, lignin, cellulose, hemicellulose, nitrogen-free solubles, and ash according to standard AOAC methods. Analyses were performed on roots, stems with remaining leaves, burrs, seed, and lint. While the total caloric content per 100 g remained nearly constant, the percent by weight and in calories of vegetative tissues decreased from 59% for the earlier cultivars to 44% in modern cultivars. The change could be attributed to the genetically based increase of lint calories while those of roots, stems, burrs, and seeds were decreased or remained relatively unchanged. The plant did not change markedly in photosynthetic capability, but its capability to apportion energy to lint production increased.