The dairy industry is composed mostly of independent farmers who make the milk production decisions. However, like most livestock sectors, the industry is becoming more concentrated with fewer farms and larger herd sizes. Farms with more than 2,000 milk cows account for almost 2/3 of milk production.
Minnesota, Michigan, New York, Pennsylvania, and Wisconsin are the traditional dairy states and continue to be large producers. Other states, particularly in the western U.S. (California, Idaho, New Mexico, Texas, and Washington) represent an increasing share of production.
There are 13 million milk cows and heifers on dairy farms, which generate an estimated 27 million tons of manure annually. Most of the manure is used as fertilizer for crops and pastures, but could also be used to produce bioenergy and bioproducts. Over 2,600 dairy farms (nearly 40% in California) have been identified as good candidates for biogas collection and bioenergy production.