Alto Dairy Cooperative (ADC) was a farmer-owned dairy cooperative in Waupun, Wisconsin. Founded in 1894, it is the oldest farmer-owned cooperative in the state of Wisconsin and boasts the nation's largest cheese producing plant east of the Mississippi River. As of 2007, ADC had two cheese plants, one in Black Creek and one in Waupun, as well as 467 employees. The cooperative has a membership of about 500 farmers. In 2007, it handled $378 million in sales and had a net income of $19.6 million.