An acre of potatoes at the average yield for the United States in recent years will produce enough calories to feed a normal adult for two years if he could live on potatoes alone. Using modern machine methods, this acre of potatoes can be produced with 83 hours of man labor, 73 of horse labor, and 7 of tractor labor. The labor that went into producing machinery, fertilizer, sprays, seed, and other supplies used can be roughly estimated at 40 hours. Thus in a pure potato economy, and if we assume that labor would be as efficiently used in such an economy as at present, the present total labor force of the United States would need to work only 20 minutes per day to produce all the food the present population would need.
For this last statement, however, we would really need to make one more assumption, that enough good potato land would be available to produce the 150,000,000,000,000 calories of potato food needed. The United States has a wealth of land that could be turned to growing potatoes. The two to three million acres planted in the 30 late-potato states is a very small percentage of the 200,000,000 acres in crops in the 30 northern and western states whose climate is more or less suited to potato growing. These circumstances point to the conclusion that the production of potatoes can always be expected to press closely on the price.
Moreover, if the per capita output of our population expands, we can expect less of the diet to consist of potatoes and the per capita production to decline. Our people will more and more get into an income state in which they will eat potatoes only because they like them, or need them for a wellrounded diet, or for a while from habit; and not because they are a cheap source of calories. As a matter of fact, the potato consumption of a third or more of our population is largely on this last basis at present.
The truth of the last statement is attested by the evidence of Chart 88.