In the deserts of the west, just after the turn of the century, steam and gasoline-powered tractors replaced mules as the motive power for wagon trains. Our photo shows trains pulled by two Best Round-Wheel Model 75 tractors, carrying what appeared to be half-sections of large-diameter pipe, the type used on big water projects.
The round-wheel version of the Best 75 was a bit of a rarety, as the majority of this model were built as tracked machines. Produced by the C. L. Best Company between 1914 and 1919, these machines have a lineage reaching back to the 1870s, and a heritage still alive today in Caterpillar Tractors. Best Manufacturing Company was founded by Daniel Best in 1871, but soon found itself fiercely in competition with the Holt tractor company, owned by brothers Charles, Benjamin and Frank. Soon accusations of patent infringements flew, and the two companies headed to court in 1905. As a result, they ended up deciding to merge under the Holt name in 1908 but with Best's son, Clarence Leo Best, serving as president of the San Leandro, California, factory.
Given the manufacturing dates, this puts the Los Angeles Aqueduct out of contention for the location of this photo. But, there were plenty of other large western water projects that used such equipment.
Only one round-wheel Best 75 is known to have survived, and photos can be seen on the Steel Wheels website (and big thanks to webmaster David Parfitt for the research help!).