Ever since we started rearranging the surface of the earth, there has been a need to push piles of dirt and rock and, especially, to push it into holes or over the edge of a bank.

It could certainly be done with hand tools, but only with great effort and much time. The difficulty arose with how to do it mechanically.

On Thanksgiving Day, 1904, grain harvester manufacturer Benjamin Holt tested a new earth moving machine on a farm near Stockton, Calif.

By the time he finished his experiment, more than just earth moved.
The invention of the dieselpowered traction machines that could move over land too soft to support horsedrawn or wheeled tractors caused a revolution not only in the farming business but in the construction and military businesses as well: Holt's trackdrive principal was applied later to everything from bulldozers to the World War I military tank.

In celebration of the 75th anniversary of that tractor, the Smithsonian Institution's Museum of History and Technology put on display last week a 1929 Caterpillar tractor called the "cat 10."

It was a merger of the Holt Manufacturing Co. and the Best Tractor Co. in 1925 that created the Caterpillar Tractor Co., which is today the largest crawlertractor manufacturing firm in the country.

Horses were great at pulling machinery, and did reasonably well with pull graders to spread material behind them as they walked. But how to use horses to spread material ahead of them?

Some say the first bulldozer was invented in 1904 by Benjamin Holt who developed an endless chain tread for his steam engine. Around the same time, the Hornsby Company of England also patented their version of a bulldozer which was closer to what is known today as a bulldozer because it was steered by controlling power to each track.