Every 5 years, the USDA conducts a national census of agriculture. The USDA defines a farm as "any place from which $1,000 or more of agricultural products were produced, sold, or normally would have been sold" during the year the census was conducted. Properties that meet this definition are statistically sampled as part of the USDA national census.

In 2007, there were just over 2.2 million farms in the U.S.