Caterpillar Tractors: Roots in Delta Peat Soil

The gasoline-powered Holt 75 Caterpillar was the best-selling of the Holt tractors from 1914 to 1924. It established a reputation as a quality farming tractor and was proven in World War I by hauling artillery and ammunition.

Holt 75 arrives at San Joaquin Co. Historical Museum, August, 2010. (Photo by D. Stuart, SJCH Museum)

The San Joaquin County Historical Museum recently completed almost nine years of work to fully restore a Holt 75 Caterpillar tractor. The track-type tractor was manufactured in Stockton and sold in 1919 to Barrett Brothers farms in Antelope (just north of Sacramento). It was used into the 1930s and was donated by the Barrett family to the Museum. Why would volunteers and staff put years of work into the frame-off restoration of a hundred-year-old tractor? What is its connection to the Delta? Here’s the story…

Benjamin Holt (1849-1920) was president of The Holt Manufacturing Company of Stockton and is credited with perfecting the design of the track-type tractor, or “Caterpillar.” The Caterpillar tractor is recognized as an engineering landmark by both the American Society of Mechanical Engineers and the American Society of Agricultural and Biological Engineers.  

Benjamin Holt. (Holt-Atherton Special Collections, University of the Pacific)

The first practical field trial of a track-type tractor took place along Mormon Slough, near The Holt Manufacturing Company plant in Stockton, in November 1904. The not-yet-named Caterpillar was developed to work the peat soils of the Sacramento-San Joaquin Delta, but revolutionized equipment used in agriculture, construction, logging, and warfare around the world.

Holt’s three older brothers came to California from New Hampshire in the 1860s and set up family businesses in San Francisco. Young Benjamin joined them in 1883, and with his brother, Charles, formed the Stockton Wheel Company. The Holts initially manufactured wooden wagon wheels; they added combined harvesters in 1886 and steam traction engines in 1890. But it was the Caterpillar that had worldwide impact.

Testing first steam prototype on Roberts Island, 1904. (Special Collections, UC-Davis Library)

The Swamp and Overflowed Lands Act of 1850 conveyed ownership of the Delta wetlands to the new State of California. By the 1870s, most of Delta land was privately owned—often by companies financed by urban absentee investors, companies that could afford to build levees to “reclaim” the rich peat soils for agriculture. Many reclamation districts were formed and by the turn of the century most of the Delta islands and tracts had been encircled by levees.

The reclaimed tracts had to be drained, cleared of marshland vegetation, and tilled for planting. The soft peat was often muddy and was so friable that it was difficult for draft animals to negotiate, even when dry. Inventors tried to support the fifty thousand-pound, steam-powered, iron-wheeled traction engines (tractors) of the 1890s by extending the width of the wheels. Some machines grew to be more than forty-five feet wide and became quite difficult to maneuver.

The solution, perfected by Benjamin Holt, was to replace the wheels with oblong tracks, tracks that distributed the weight of the tractor over a much bigger contact area than did wheels and which provided much greater traction.

Holt steam tractor with wheel extensions, ca. 1900. (San Joaquin County Museum)

More than one hundred patents for track-type vehicles had been issued before Benjamin Holt’s, but none of those machines had proven successful in the field. The earliest documentation of a track-type machine is an 1825 patent for a tracked cart in Great Britain; Benjamin Holt and his nephew Pliny traveled to England in 1903 to see tracked vehicles there. A steam-powered track-type tractor was exhibited at the California State Fair in 1858, but the inventor, Warren Miller of Marysville, never produced more than that one. In 1900, Alvin Lombard built a steam-powered track-type tractor to haul logs over the snow in Maine, for which he obtained a patent in 1901. Benjamin Holt learned from all these earlier efforts.

For the 1904 test in Stockton, Benjamin Holt had engineers remove the rear wheels of a steam-powered traction engine and replace them with a set of tracks he had designed. The machine performed well in the mud of Mormon Slough, so it was taken to the Holt ranch on Roberts Island in the Delta west of Stockton and was operated all winter. 

Testing gasoline prototype in Mormon Slough, 1906. (Holt-Atherton Special Collections, University of the Pacific)

Holt had improved tracks put on the prototype in March 1905. The Holt company photographer, Charles Clements, went to the ranch to photograph the experimental machine. Clements is said to have observed that it crawled like a caterpillar. To which Holt reportedly replied, “Caterpillar it is. That’s the name for it!” This great story is apparently more legend than truth. For several years after those test runs the company referred to this machine and others that followed as “mud turtle,” “paddlewheel,” “platform,” or “tread mill” engines. The Caterpillar name was not used in print until 1908 (see below), did not appear on a tractor until 1909, and was not trademarked until 1910. Regardless, the name became synonymous with track-type tractors.

After further testing six of the machines, in 1906 The Holt Manufacturing Company sold its first steam-powered track-type traction engines. That same year, Benjamin and Pliny Holt tested the first gasoline-powered track-type machines and The Holt Manufacturing Company incorporated the Aurora Engine Company to produce gasoline engines (named for its location on Aurora Street, in south Stockton). 

Within two years, The Holt Manufacturing Company had sold more Caterpillars than all the wheeled steam traction engines it had produced in the previous fifteen years. The Stockton press recognized that Holt’s Caterpillar would put Stockton on the map:  

The ‘Caterpillar’ will without question become the greatest advertisement that Stockton has ever had for achievement in mechanics, not excepting the combined harvester, for the new tractor engine will be used in all parts of the world, in the tropics and in the frozen north, and every one of them will bear the label of Stockton manufacture.” [Stockton Daily Evening Record, Sept. 25, 1908]

In 1910, The Holt Manufacturing Company completed the purchase of a bankrupt tractor manufacturer’s plant in East Peoria, Illinois, seeking to tap the Midwest and eastern markets for tractors. The Holt Bulletin of November 1, 1909, crowed about “the distinction of being the first large Western manufacturer to establish an Eastern plant.” 

Steam prototype. (Special Collections, UC-Davis Library)

The gasoline-powered Holt 75 Caterpillar was the best-selling of the Holt tractors from 1914 to 1924. It established a reputation as a quality farming tractor and was proven in World War I by hauling artillery and ammunition. The Holt manufacturing plant in Stockton grew from three hundred employees in 1909 to one thousand workers after the production of the 75 ramped up, and numbers continued to grow to about two thousand five hundred employees by the end of World War I in 1918. More than 4,000 Holt 75s were made, 1,800 of which were ordered by the military.

Volunteers restoring 1919 Holt 75 Caterpillar tractor. at San Joaquin County Historical Museum. (Photo: SJC Historical Museum)

The Holt Manufacturing Company and its long-time competitor, the C.L. Best Tractor Company of San Leandro, California, consolidated in May 1925 under the newly formed Caterpillar Tractor Company. Caterpillar production was shifted out of the Stockton plant in 1925, although combined harvesters continued to be built in Stockton into 1929, and the acclaimed Best/Caterpillar Sixty tractor continued to be manufactured in San Leandro. In 1929, Caterpillar moved the combined harvester assembly line to East Peoria, Illinois, and closed the Stockton plant. The San Leandro manufacturing plant was the focus of the innovative development of Diesel-powered Caterpillars in the early 1930s, but it too eventually suffered the same fate. 

Although the Caterpillar corporation grew into an international manufacturing powerhouse, headquartered in Illinois, its roots remain in Stockton, San Leandro, and the rich peat soils of the Sacramento-San Joaquin Delta. 


To see and  hear the restored Holt 75 in action on the 100th anniversary of its date of manufacture please follow this link for the video by Jack Jacobs, San Joaquin County Historical Museum Docent. 

(This article was condensed from: “Earthmoving Capital of the World: San Joaquin County’s Agricultural needs Led to Decades of Innovation,” The San Joaquin Historian, summer 2017, published by the San Joaquin County Historical Society. 

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