Researchers with USDA's Economic Research Service are tracking the shift of cropland into larger farms. Their method measures the midpoint of which size of farm holds the average acre of American farm ground.
In 1982, the midpoint size for all crop farms in the US was 589 acres. By 2011, that number had doubled to 1100 acres.
Between 1987 and the most recent census data in 2007, ERS found that midpoint harvested acreage on corn tripled, from 200 acres to 600 acres.