In both case A and case B it is assumed that the greatest net profit per acre is to be obtained with 160 acres, and that the net profit per acre when the farm is of that size is $5. In case A it is assumed that the net profit would decrease $1 for each 80 acres added, while in case B the decrease is assumed to be only one-half as rapid. In the first instance the net profit per farm increases until 280 acres are reached, when the net profit per farm decreases, until at 560 acres no profit would be obtained. In case B the net profit per farm increases until 480 acres are reached. Everyone is cautioned not to accept these figures as representing what would actually happen. All that can be said is that as the farm unit increases in size there will come a point at which the net profit per acre will decrease because of the physical difficulty of managing a large area, and, therefore, there is a limit to the size of a single farm. Fifteen thousand acres may lay in one tract and be owned by one individual, firm or corporation, but its economic management requires for purely physical reasons, not to mention others, that it be managed in several units more or less distinct from one another. Just what the size of this unit will be no one knows and it will vary with the type of farming, the type of farmer and many other circumstances. For example, a very common unit for a tenant cotton farm is between 20 and 50 acres, both the product and the farmer being a limiting factor. Perhaps the most important lesson to be learned from a study of this table is that it is wise for some men to operate a farm of 320 acres, others of 160 acres and still others of 80 acres, because each size of farm presents a task suited to different abilities. It would be as futile for one fitted to operate only an 80-acre farm to attempt to manage 320 acres as it would be unwise for the man capable of conducting 320 acres to confine his attention to 80 acres. Unfortunately while this principle is not difficult to perceive and is easily stated, it is practically impossible to make any application of it to an individual case. Only time and the inexorable laws of competition will adjust men to their several tasks. It will be of interest to note what influence in actual practice the type of farming has upon the size of the farm. The census reports the average size of all farms in the United States as 147 acres, with the different types as follows: Vegetables, 65 acres; fruits, 75 acres; dairy products, 120 acres; hay and grain, 159 acres; and live stock, 227 acres. Speaking in a very general way, only about one-half the land on these farms is in cultivated crops, while only 40% of the income may be from the products which cause the farm to be thus classified. The young farmer will do well to have these figures in mind when he starts out in life, for while they are not to be followed literally, they give him a measuring stick with which to compare his operations.