Because Iowa was primarily a farm state, the first industries were food processing and the manufacture of farm implements. These industries have retained a key role in the economy, with over 100,000 farms operating in the state in 2000. In recent years, Iowa has also added a variety of other manufactures—including pens, washing machines, and even mobile homes.

The estimated total value of shipments by manufacturers was $64 billion in 1997. More than 120 of Fortune magazine's "Top 500" industrial corporations have plants in Iowa, including Caterpillar Tractor, General Motors, Mobil, General Electric, General Foods, Procter & Gamble, and US Steel. Iowa is the nations top producer of beef (4%), pork (24%), corn, soybeans, and grains.

Earnings of persons employed in Iowa increased from $47.4 billion in 1997 to $49.1 billion in 1998, an increase of 3.7%. The largest industries in 1998 were services, 21.6% of earnings; durable goods manufacturing, 13.1%; and state and local government, 12.5%. Of the industries that accounted for at least 5% of earnings in 1998, the slowest growing from 1997 to 1998 was farm (6.7% of earnings in 1998), which decreased 1.7%; the fastest was durable goods manufacturing, which increased 8.7%.