The dairy industry is important to Smithfield, and in 1892 the Smithfield Dairy Company built its plant--which was later taken over by Sego Milk Products. In 1920 the Morgan Pea Factory began business and was later bought by Del Monte Foods; it has since been turned into a can-making factory. Some current businesses in Smithfield are Cantwell Brothers Lumber, Smithfield Livestock Auction, and Smithfield Implement.

A tradition in Smithfield began in an elementary school in 1925 as the Health Pageant. It has grown and developed into Smithfield Health Days, which is now an annual event and includes a parade and pageants. The population of Smithfield has steadily increased in recent years. In 1940 it was 2,461; in the 1970s the city began to grow more rapidly. According to the 1990 census there were 5,566 people in the city of Smithfield.

See: Leonard Olson, The History of Smithfield (1927).

Linda Thatcher