Knapp Plow subsoiler
Knapp Plow Company subsoiler in action (Knapp Plow Collection, History San Jose)

The plows manufactured by the Knapp Plow Company contributed significantly to the agricultural history of the Santa Clara Valley. The life of the company began in 1871 in Half Moon Bay, California, when Robert I. Knapp (1833-1904) built his first plow. During that time, many farmers were growing potatoes on the hills along the coast. They plowed the sides using a Kilgore reversible plow (sometimes called sidehill plow), with a cast iron bottom, which was found to be problematic and ineffective.

As a blacksmith, wheelwright, and wagon maker, R. I. Knapp served many farmers who took their Kilgore plows to him for service. In response, R. I. Knapp built a reversible plow which had a carbon steel bottom, hardwood beam and handles, cast iron standard, and a locking device to stabilize the plowshare. Patented in 1875 and again in 1882, Knapp’s plow was so successful that between 1878 and 1907 it won 14 awards at county and state fairs, as well as at the World’s Exposition in New Orleans.

In 1900, Knapp’s son, Horace G., became a partner in the company. With that change came a new company name: R. I. Knapp and Son. Four years later, however, R. I. Knapp died, and H. G. Knapp promoted his son as partner. The company became H. G. Knapp and Son, and in 1907 it was relocated to San Jose, CA, in order to expand its customer base.

Knapp Plow Works
Knapp Plow Works, 1022 South First Street, San Jose (Knapp Plow Collection, History San Jose)

The company soon diversified its product line to include numerous types of agricultural implements: orchard, subsoil, ditching, and gopher plows, among others. However, after the patents for the original reversible plow expired, several companies began manufacturing exact duplicates. In the midst of this competition, the family company changed its name to Knapp Plow Works in about 1915 and then Knapp Plow Company in about 1922. By 1922, Eastern plow companies were building and selling plows similar to those of Knapp at much lower costs. These forces caused Knapp Plow to lose much of its market share, and in 1924, the family business ended after fifty years of service. Though the company that developed around the first Knapp Reversible Plow was not large — employing 45 workers in its heyday — it was important locally, and its plows were widely used.

Clyde Arbuckle and the Knapp Plow
Clyde Arbuckle demonstrating the restored Knapp plow at History San Jose ca. 1955 (History San Jose Photographic Collection)

The Knapp Plow Company Records at History San Jose contain materials relating to the marketing and design of the various plows built by the company between 1912 and 1922, when the company was active in San Jose. In addition, the Norman E. Knapp Papers (1946-1947) contain materials documenting the development of the 2-Bottom Offset Disc Plow (Model 402) and the Stabilizer. Norman Knapp worked for his father Horace in the family plow business until the company closed in 1924. After the closure, he was employed as a roustabout in the oil fields near Coalinga, but he returned to San Jose in 1938 to work for Westinghouse.

In retirement, Knapp built exact duplicates of the early Knapp Reversible Plow, one of which was donated to the Smithsonian in Washington, D.C., in 1970. Born into an innovative family, Knapp was also an inventor. He is recognized for the creation of the Stabilizer which keeps the shares of plows deep in the soil. Though Knapp worked just a short time at the Knapp Plow Company before its closure, his interest in plow manufacturing never subsided. The material belonging to this collection imparts his personal achievements in plow building.

Download the Guide to the Knapp Plow Company Records and Norman E. Knapp Papers (MS Word).