Taking all this into account , what might we reasonably estimate supermarkets to be like in the year2001? To begin with , the world food supply is going to become steadily tighter over the next thirty years—even here in the United States.By2001 , the population of the United States will be at least two hundred fifty million and possibly two hundred seventy million , and the nation will find it difficult to expand food production to fill the additional mouths. (4) This will be particularly true since energy pinch will make it difficult to continue agriculture in the high energy American fashion that makes it possible to combine few farmers with high yields .