Other trends and inventions had also helped make it possible for Americans to very their daily diets.Growing urban populations created demand thatencourage fruit and vegetable farmers toraise more product.Railroad refrigerator cars enabled growers and meat packers to ship perishable great distances and to preserve them for longer peroids. Thus ,by the 1980s northrn city dwellers could enjoy southern and western strawberries ,grapes, nd tomestoes , previously available for a month at most for up to six months of the year.