The breeds of chickens are generally classified as American, Mediterranean, English, and Asiatic. While there are hundreds of breeds in existence, commercial facilities rely on only a select few that meet the rigorous demands of industrial production. The single-comb White Leghorn, a Mediterranean breed widely used throughout the global egg industry, is a prolific layer that quickly reaches sexual maturity. The Cornish Cross, a hybrid of Cornish and White Rock, is one of the most-common breeds for industrial meat production and is esteemed for its compact size and rapid, efficient growth. Small farms and backyard flocks utilize a much wider variety of breeds and hybrids. Common American breeds include the Plymouth Rock, the Wyandotte, the Rhode Island Red, and the New Hampshire, all of which are dual-purpose breeds that are good for both eggs and meat. The Asiatic Brahma, thought to have originated in the United States from birds imported from China, is popular for both its meat and its large brown eggs.