Benjamin Holt and the Caterpillar Tractor

I find it amazing that San Joaquin County was for fifty years or so the capital of earthmoving equipment. The County’s industrial, transportation, and financial infrastructures came into existence shortly after the Gold Rush, during the dry-farmed grain era. But it was the reclamation of rich peat soils of the Sacramento-San Joaquin Delta and the switch to irrigated, intensive agriculture that provided a need for new kinds of heavy machinery that inventors and entrepreneurs like Robert G. LeTourneau and Benjamin Holt helped fill.

Testing gasoline-powered Caterpillar prototype in Mormon Slough, Stockton, California, ca. 1906.

Benjamin Holt (1849-1920), president of the Holt Manufacturing Company of Stockton, is credited with perfecting the design of the track-type tractor, or Caterpillar. 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 originally manufactured wooden wagon wheels, then added combined harvesters in 1886 and steam traction engines in 1890.

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 "Caterpillar" was developed to work the deep peat soils of the Sacramento-San Joaquin Delta, but it revolutionized equipment used in agriculture, construction, road building, and logging around the world.

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 Holt had it taken to the Holt ranch on Roberts Island, west of Stockton, where it operated successfully all winter.

Holt Manufacturing Company sold its first steam-powered track-type traction engines in 1906. That same year, Benjamin and his nephew, Pliny Holt, tested the first gasoline-powered track-type machines, and the Company incorporated the Aurora Engine Company (named after its location on Aurora Street in Stockton) to produce gasoline engines. Within two years, the Holt Manufacturing Company had sold more Caterpillars than all the wheeled steam traction engines it had produced the previous fifteen years.

The San Joaquin County Historical Museum will present the Benjamin Holt story as part of a long-term exhibit on the history of earthmoving equipment in the County. You can currently see a preview in the Museum’s Brown-Jones Building. Please contact me by e-mail ( if you would like to donate funds, ideas, stories, photos, or artifacts for the final exhibit.

David Stuart is the executive director and CEO of the San Joaquin County Historical Society and Museum.

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