Shamrock’s rich heritage began when W.T. McClelland (Mr. Mac), son of an Irish farmer, immigrated to the U.S. and bought a small dairy business in 1920 to serve a handful of customers in the Tucson area. His wife, Sara Winifred (Winnie) became the bookkeeper and christened the new business Shamrock Dairy. Together, Mr. Mac and Winnie forged an American success story.

After World War II, Shamrock Dairy built a processing plant in Phoenix and launched continuous expansion programs in both facility development and product line. Over the years, the product line has emerged to include frozen foods, fresh fruits and vegetables, meats, fish and institutional foodservice supplies and equipment.

Today, Shamrock Foods Company is the umbrella for Shamrock Farms, the largest dairy in the Southwest, and Shamrock Foods, a nationally ranked foodservice distributor. Now headquartered in Phoenix, Shamrock sends refrigerated trucks to 9 other states from distribution centers in Phoenix and Commerce City (Denver) Colorado.