Ag History 1970-1990 By Christopher Blantz 1970 Average population Total U.S. population: 204,335,000; farm population: 9,712,000. 1980 Average population Total U.S. population: 227,020,000; farm population: 6,051,000 1990 Average population Total U.S. population: 261,423,000; farm population: 2,987,552