The USDA and the Economic Research Service look at 100 years of American eating. Graph above on meat eating habits. Another point of interest:
Increasing availability of fats and oils and cheese reflects their use in processed foods and the growing eating-out market in the second half of the century. The availability of fats and oils grew from 36 pounds per person in 1909 to 87 pounds in 2008. Much of this increase was in salad and cooking oils used to cook french fries, a mainstay of fast food and other restaurant menus. Cheese availability also skyrocketedgrowing from 11.4 pounds per person in 1970 to 31.4 pounds in 2008. Cheese owes much of its growth to the spread of Italian and Mexican eateries in the United States and to innovative, convenient packaging, such as string cheese for lunch boxes.
(Hat tip: Kottke)