Swine are valuable for their flesh, prepared as ham, bacon, and pork, and for their fat (lard); they also provide many other products, e.g., leather for gloves, footballs, and other articles, and bristles for brushes. Hogs are commonly grouped as meat-type or lard-type, with the former dominating the U.S. farms. Hogs are raised in nearly all parts of the United States, but the corn belt of the Midwest is the chief hog-raising area, with Iowa by far the leading hog-producing state.
A great majority of U.S. hog production has moved from open pens to enclosed, mechanized facilities. The trend is toward huge, factorylike hog farms where swine are born and bred inside structures that feed, water, and dispose of wastes while controlling ambient temperature. Though hogs will eat almost any food, modern swine feed is nutritionally balanced to produce rapid and healthy growth. Based on a mix of corn and soybeans, the feed is supplemented by minerals, vitamins, and antibiotics. The giant modern farms produce enormous amounts of hog waste; this has become of increasing concern as a potential source of water pollution.